Trying to share information with people on your Web-based networks can introduce another layer of digital jujitsu. It can be awkward to snag a photo or a snippet of text from one Web site and send it to a friend in a social network on another, or post it to your own blog.

But I’ve been testing a little-known Web browser that attempts to solve these problems. It’s called Flock, and it bills itself as “the social Web browser.” I found that it worked well, but it isn’t for everyone, and it has some important downsides.

Flock is a modified version of the excellent Firefox Web browser that tacks on some special features for social networkers and bloggers. It’s available free at flock.com in essentially identical versions for Windows, Mac and Linux.

Flock adds a special vertical “sidebar” at the left of the browser that keeps your social networks, photo sites or news feeds visible at all times, regardless of what page you’re viewing in the main browser window.

For instance, with Flock, you can see that you have a new friend request in Facebook, or that a pal has posted new photos in Flickr, without clicking away from reading this column in the main browser window.

But, wait: There’s more. With one click, you can display a horizontal “media bar” across the top of the browser containing thumbnails of all of a friend’s photos or videos from a social-networking or photo site, again without changing what’s in the main browser window.

These two special bars also allow you to take action. For instance, you can just drag images and text from Web pages into the sidebar to share them with friends listed there. And any photo on the media bar can be quickly emailed or posted to a blog.

There’s also a “Web clipboard,” which can save any text, image or link from a site in the main window by merely dragging it to the Flock sidebar. Once an item is in this clipboard, it stays there until you delete it.

Flock has its own built-in blog editor, which allows you to quickly compose, edit and publish blog posts containing interesting items you encounter on the Web. And it creates a special personal Web page, called My World, which combines your social-networking updates, news feeds and photos.

I found Flock productive and fun to use. I tested its special sidebar with my Facebook, Flickr, Picasa and YouTube accounts, and with my favorite news feeds. I also used another of Flock’s features, which let me check my Gmail and Yahoo Web-mail accounts without navigating to their main pages. And I published several posts from within Flock to a test blog I maintain. All of this worked as promised.

In my tests, I used the latest edition of Flock, version 2.0, which is built on the new Firefox 3.0 browser. Even though this latest iteration of Flock is still in beta status, I found it to be quite stable.

But Flock isn’t for everyone, and it has some significant drawbacks. For one thing, you’d need a fairly large or high-resolution monitor to accommodate the Flock sidebar and media bar without reducing the size of the main browser window so much as to require too much scrolling. Even with a big or high-res screen, you will see fewer toolbar links and browser tabs than normally.

And, Flock has a busy, even frenetic, look that can be distracting and annoying. So many things are going on at once that it can be hard to concentrate on the main attraction: the Web page you are reading in the main window.

Also, while Flock does indeed spare you from clicking back and forth as often among tabs in your browser, it doesn’t entirely eliminate clicking around. Its sidebar can display only one type of information at a time — social networks and photo-sharing sites in one view, news feeds in a second, the clipboard in a third, and Web bookmarks in a fourth. So you’ll have to click the sidebar’s own controls fairly often to check all of these, or keep going to the special My World page in the main window.

Finally, Flock works with only certain social networking, photo-sharing and blogging services. While it does support most of the main ones, there are some glaring omissions. MySpace isn’t yet on the list, though it’s expected to be added next month. But Hotmail, Windows Live Spaces and SmugMug, among others, are missing. And it doesn’t support any instant-messaging services at all.

Flock does a good job at the tasks it sets for itself, but I would recommend it for only the heaviest and most impatient social networkers. For most others, Flock is overkill.

Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

So, last month, the photo giant introduced Photoshop Express, its free Web-based service for storing, sharing and editing photos, in an effort to compete with established online photo services such as Yahoo’s (YHOO) Flickr, Google’s (GOOG) Picasa Web Albums, or the photo-laden Facebook social-networking service.

Photoshop Express has many of the same features as Flickr and its ilk. It gives you two free gigabytes of photo storage. But Adobe is hoping to make its mark with editing.

Most online photo services offer little or no editing, assuming you’ll do that using software on your computer before you upload your pictures. But Photoshop Express, borrowing from Adobe’s deep knowledge of photo editing, offers the nicest set of Web-based editing tools I have seen. They are sophisticated for a consumer application, yet easy to use. They edge out those in Picnik, a pioneering Web-based photo editor I hailed last year.

These slick editing tools are not only available for use with photos you’ve uploaded from your hard disk. You can also use them to edit pictures stored in your accounts at Facebook, Picasa Web Albums and another big photo-storage service, Photobucket — all without leaving Photoshop Express. You can even move pictures between Photoshop Express and these three services just by dragging and dropping.

Adobe’s new service is available in the U.S. only, at www.photoshop.com/express.

I’ve been testing Photoshop Express and its service overall is pretty good, even though it’s still labeled “beta.” It’s a nice example of the Web 2.0 trend, where programs accessed via a browser can look and feel like applications that live on your computer.

But Photoshop Express is rough around the edges. It can be slow at times, and it’s missing some obvious features, like the ability to easily download publicly shared pictures from other members or to print photos. Adobe says it is working on these things.

Photoshop Express isn’t meant to replicate all the features and power of Photoshop. It’s more like a Web-based version of Photoshop Elements, Adobe’s consumer software package.

I tested Photoshop Express on multiple computers: PCs running Microsoft’s (MSFT) Windows XP and Windows Vista, and Macs running Apple’s (AAPL) Leopard operating system. I used it in all three major Web browsers: Internet Explorer for Windows, Firefox on both Windows and Mac, and Safari, also on both platforms. It worked fine in all of these operating systems and browsers, though it does require Adobe’s free Flash software.

For my tests, I uploaded from my computers dozens of photos, from very large images captured with good digital cameras to smaller shots from cellphones. All were handled perfectly by Photoshop Express. I also opened and edited pictures in Photoshop Express from my accounts on Picasa Web Albums and Facebook. All of this worked well, though uploads of large images can be slow if your Web connection is pokey.

Photoshop Express is a handsome product, presenting your photos on a gray background with controls and features arrayed at the top and bottom, and down the sides, in a logical, clear manner. Your own photos are presented in a section called “My Photos,” and can be organized into albums. Photos that other Photoshop Express users have chosen to publicly share are organized into collections called “Galleries,” which can include multiple albums. You access these community photos by simply clicking on “Browse” or performing a search.

For each album you create, you can choose to share it publicly or to keep it private. Whichever option you choose, you can email friends either a link for viewing the album or a single photo. Your own photos can be downloaded at a variety of resolutions, including original size.

When you view shared galleries or albums, they appear as slide shows. You can select a number of slick effects by which the slides appear, allowing them to zoom and glide into place from various directions.

The editing features really stand out. In addition to standard tools such as auto-correction and red-eye elimination, Photoshop Express lets you touch up areas; adjust exposure, saturation, and lighting; and even make certain colors pop — so grass is greener, for instance. And, in most cases, it shows you small example images illustrating the changes, then previews those changes in the larger main image just by moving your mouse over the example. You can revert to your original at any time.

Unfortunately, there are a number of problems. Photos, especially large ones, can take awhile to appear in the editing module and to snap into focus. Captions sometimes get lost or mixed up when you move photos to other services. You can view shared albums only as slide shows, not as individual photos.

Still, Adobe has made a good start with Photoshop Express, and it’s worth a try if you want better online editing for your pictures.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Such Web-based software has existed for years, but it was clumsy, slow and simplistic — no match for locally installed software. Common techniques, such as dragging items around the screen, were impossible. Seeing the results of an action often required the Web page to reload.

Now, developers are churning out Web-based applications that are so fast, rich and smooth they can hardly be distinguished from standard programs. And because they live online, these Web applications can be constantly updated; can run on both Windows and Mac computers; and can be easily integrated with other Web sites and services.

One of the best examples of these slick new Web-based application is Picnik, a sophisticated, photo-editing application offered free of charge at picnik.com. I have been testing Picnik and I like it a lot. It’s a fast and impressive program for tweaking and improving your photos, then posting them to popular photo Web sites, saving them to your own computer, emailing them, or even printing them.

Picnik, which comes from a small Seattle company called Bitnik, isn’t meant to compete with Adobe Photoshop, or to serve professional photographers or dedicated hobbyists. Instead, it’s for the same casual photographer who would use the limited editing tools in Apple’s iPhoto or Microsoft’s Windows Vista Photo Gallery.

Picnik isn’t a place to store your pictures, or a way to organize them — yet. The company says it will consider adding these features down the road. For now, it is focused on being an editing complement to popular Web services — such as Yahoo’s Flickr, Google’s Picasa Web Albums, and the independent Facebook — that already allow for storing and organizing photos. You could also easily use it as the main editor for photos you store on your hard disk.

The program is currently in beta, or test, phase, though in my tests it worked smoothly and surely. During this beta period, all of its features are offered for free. Later this summer, the company expects to end the beta period and begin charging something like $20 or $25 a year for access to some of the more rarified special effects that Picnik offers, though the core editing and sharing functions, and some of the effects, will remain free.

In my view, Picnik has a beautiful and responsive user interface that worked perfectly on the multiple Windows and Macintosh computers I used to test it. It worked equally well in the latest versions of the three best-known Web browsers: Microsoft’s Windows-only Internet Explorer, Mozilla’s Firefox (on both Windows and Mac) and Apple’s Safari (on both Mac and Windows.)

Picnik uses a simple tabbed interface across the top to navigate among its major functions. Edits and changes are previewed in real time, instantly, without the need for a page refresh or reload. Actions are confirmed with translucent messages that pop up on the screen and fade gracefully.

Any edit or special effect can be undone or redone instantly, all the way back to the original version of the picture, which Picnik retains on its servers during the editing process.

For example, you can zoom in or zoom out on a picture with a slider that works just as it would in a local program — the effect is immediate, with no jerkiness. If you wish to crop a picture, a pane representing the region to be included in the crop is superimposed on the photo. Everything inside the pane is sharp and clear, and everything else is faded a bit. This pane can be dragged, or resized, in real time.

Another example: If you want to tint a picture, the program shows you a color palette with a white dot you can move around the palette to pick your tint. As you do this, or move a slider that controls the intensity of the tint, the changes are instantly previewed in the picture.

None of this is unusual for a standard photo program installed on your computer, but it is impressive to see these effects happen so quickly and interactively in a program functioning over an Internet connection.

Picnik’s makers have struck partnerships with Flickr, Picasa and Facebook, and you can easily fetch pictures from these sites and post new pictures or edited versions of the originals back to the sites. You don’t need to switch to the sites themselves, they appear inside the Picnik Web page.

You can also upload pictures for editing from any other Web site, or from your hard disk, and you can email pictures to friends or to a wide variety of other sites, such as PhotoBucket, SmugMug and Snapfish.

The designers of Picnik have done such an elegant job that I wish the site would allow storage of photos, or organization of photos across your multiple online accounts and your hard disk. If you want to see how good a Web application can be, take Picnik for a spin.

• Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.

The FlipStart is part of a new wave of tiny Windows PCs, which include the second version of a machine called the OQO, the Ultra-Mobile PC from Samsung and Sony’s UX series. For a decade or more, the computer industry has been trying to come up with an ultracompact computer that can use standard operating systems and software. They have failed to catch on broadly for several reasons.

First, they are an awkward, in-between size: too large to fit in a pocket, but too small to allow for minimally comfortable touch-typing keyboards. Second, their screens are often too small to handle the navigation through multiple windows that Windows requires. Third, their battery life has been poor. Finally, they’ve been very costly.

I’ve been testing the FlipStart and found that while it overcomes some of these issues, it can’t lick all of them. It runs Windows OK and it even has decent battery life. Its screen resolution and navigation are also pretty good. It weighs just 1.75 pounds, and is smaller in length and width than a standard paperback novel.

But its price, $2,000, is very expensive for a computer that’s too small to be very good for typing, yet isn’t small enough to be extra portable. Part of the size problem is that it’s thick — thicker than a 400-page paperback. And I found its keyboard to be too little and crude for laptop-style typing, but too wide for fast thumb typing, like people do on a BlackBerry. It also exhibited some funky behavior in my tests.

So, like its predecessors and competitors, the FlipStart is likely to be a novelty or niche product. It may be popular with some techies, but it’s no match for a small standard laptop, like Lenovo’s X models, which start at $1,250, are 2.7 pounds, are thinner than the FlipStart, and include a great keyboard and a screen that’s more than twice the size of FlipStart’s.

The FlipStart, which goes on sale March 27 on the company’s Web site, flipstart.com, is also much larger and heavier than the new second model of the OQO, which weighs just one pound. The new OQO, on sale next week at oqo.com, is also less costly, starting at around $1,500. Like the OQO, the FlipStart can also run the new Windows Vista, as well as Windows XP.

The FlipStart is designed as a clamshell, with a flip-up lid, like a laptop. It can be used in an L-shape, like a laptop, on a desk or table. The OQO’s keyboard slides down from behind its screen and you type on it while holding it vertically, like a smart phone. The FlipStart can be used that way, too.

The FlipStart’s 5.6-inch screen is bright and vivid, and it has a resolution of 1,024 by 600, less than most laptops, but much better than the new OQO’s. There’s a zoom feature that can be adjusted with a handy scroll wheel on the side, which is also used for scrolling through text.

There’s also a second, tiny screen in the lid, so you can see your email, contacts and calendar when the FlipStart is closed. Special navigation software on the main screen offers the same information.

In my tests, the FlipStart handled Microsoft Word, the Firefox Web browser, Picasa photo software and Apple’s iTunes quite well.

In my tough battery test, in which I turn off all power-saving software, turn on the Wi-Fi, crank up the screen brightness and play music endlessly, the FlipStart did surprisingly well. It clocked in at about 2.5 hours, which means you’d get three hours or more with typical usage. The slimmer, lighter new OQO got just 1 hour, 48 minutes.

The FlipStart includes both Wi-Fi wireless networking and a built-in cellphone modem that uses the fast EV-DO network. Both worked in my tests, as did wired networking via a snap-on port replicator that lets you connect a full-size monitor, keyboard, mouse and speakers.

But I ran into some problems. The unit too often failed to connect to Wi-Fi networks. Also, at one point, the FlipStart logged me out of Windows every time I typed the letter “L” in any program. Microsoft Outlook crashed on me repeatedly.

The keyboard, despite its typing flaws, has some nice aspects. It includes a touch pad and a pointing stick, to replace a mouse, and special keys for quickly performing various functions, such as getting to the desktop and switching open windows. But for thumb typing, I much preferred the OQO keyboard, even though it’s smaller and even though FlipStart commissioned a study showing its keyboard was better.

I think the solution to making better hand-held computers is in ever-more-potent smart phones, like Apple’s forthcoming iPhone, rather than in shrunken laptops like the FlipStart.

• Email me at mossberg@wsj.com. See video versions of my reviews at wsj.com/mossbergvideo.

Now, there’s an even better approach to running Windows on a Mac. It’s called Parallels Desktop for Mac, and it’s from a small Herndon, Va., company called Parallels. It emerges from testing today and goes on sale for $79 at the company’s Web site, parallels.com.

I’ve been testing Parallels Desktop on a new MacBook Pro laptop, and have found it works very well, despite a few drawbacks. I prefer it to Apple’s solution, even though the Apple approach is free and also works very well.

Apple’s system, called Boot Camp, has one big limitation: It allows you to run only one of the two operating systems at a time, requiring you to reboot the computer to switch between them. As a result, you can’t quickly jump between Mac programs and Windows programs. You can’t, for instance, simultaneously download your corporate email in Outlook using Windows while editing a home video in iMovie using the Mac OS.

With Parallels Desktop for Mac, you can do this. You can run any combination of Mac and Windows programs at the same time, on the same screen. No rebooting is necessary. You can even cut and paste material between Mac and Windows programs, and share files between the two environments.

The Parallels approach, called virtualization, runs Windows, with all its features, inside a window in the Mac operating system. It creates a faux Windows PC, called a “virtual machine,” that co-exists with Mac OS X. You can devote the full screen to either operating system or you can reduce Windows, and whatever programs it’s running, to a window on the Mac that can be dragged anywhere on the screen and made as small or as large as you like.

Unlike Boot Camp, Parallels Desktop can run every version of Windows back to Windows 3.1, not just Windows XP. It can also run Linux and even older operating systems like OS/2 and MS-DOS. You can even create and run multiple virtual machines, with different operating systems inside, up to the limit of your Mac’s memory.

Virtualization isn’t a new concept, and it’s not even new on the Mac. Microsoft offers a product called Virtual PC for Mac that runs Windows inside a window on older, pre-Intel Macs. But Virtual PC runs painfully slowly on these older Macs, and it can’t run every Windows program. It doesn’t run at all on the new Intel-based Macs.

Parallels Desktop runs Windows a little more slowly than Apple’s Boot Camp does because it is accessing the Mac’s hardware through the Mac operating system rather than directly, as in a dual-boot system. But, in my tests, it was very snappy, as fast as many regular Windows computers.

Inside my virtual Windows machine, I was able to run programs like the Windows version of Microsoft Office, the Windows versions of the Firefox Web browser, iTunes, Adobe Reader, Google Earth and more. All worked well, as did Microsoft’s Internet Explorer Web browser, Google’s Picasa photo program and Google’s Google Talk instant-messaging software.

I was able to do email in Apple’s Mail program while simultaneously watching a baseball game in Internet Explorer inside my Parallels Desktop Windows virtual machine. I wrote part of this column in the Windows version of Microsoft Word and part in the Mac version, cutting and pasting between the two.

And, unlike Boot Camp, Parallels Desktop doesn’t require you to dedicate a fixed section, or “partition,” of your hard disk to Windows. Its virtual Windows computer is contained in a big Mac data file that uses only as much space as Windows needs.

Setting up Parallels Desktop is fast and easy, though some novice users may find the program’s terminology a little daunting. As with Boot Camp, you have to supply your own copy of Windows to install once you create the virtual machine. And because the virtual Windows machine created by Parallels behaves like a real Windows computer, you have to install the usual raft of Windows security software.

So what are the drawbacks? I couldn’t eject a CD in Parallels without switching back to the Mac environment. Parallels treats fast USB 2.0 ports on the Mac as if they were slower USB 1.1 ports. It doesn’t support Microsoft’s DirectX technology, which many games rely on. The company pledges to fix these things in future versions.

Also, if you elect to use the optional file-sharing feature, your Mac data files could be corrupted or erased by a Windows virus. For that reason, this feature is turned off by default.

Still, Parallels Desktop is a very good product and a pleasure to use. It’s like having two computers in one, the best of both worlds.

• Email me at mossberg@wsj.com.