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.

The result is a polished, fairly powerful email program that I prefer to Google’s much-hyped Gmail, which is undergoing an even longer gestation. It has been in beta status since April 2004.

I’ve been testing the new Yahoo Mail on both Windows and Macintosh computers. It has some downsides, but it beats Gmail, in my view, both in terms of features and in terms of its ability to act like a standard computer program rather than a Web page, something for which Gmail often gets more credit.

A closer competitor to Yahoo Mail is actually Microsoft’s Hotmail, now called Windows Live Hotmail. But Yahoo tops Hotmail, too, in my opinion.

The new Yahoo Mail, which works in Internet Explorer and Firefox on Windows, and in Firefox on the Macintosh, is now more than just an email program. Like Gmail, but unlike Hotmail, it has a built-in instant-messaging module. You can choose to communicate with any of your contacts via a real-time chat, right from within Yahoo Mail, as long as that contact is online and has an IM account on either the Yahoo or Microsoft instant-messaging networks. You don’t need to be running your IM program.

Unlike either of its competitors, however, the new Yahoo Mail also allows you to exchange text messages with people on cellphones, although the message exchange must be initiated from Yahoo Mail.

Yahoo Mail offers unlimited storage of emails and attachments free of charge, and a very fast and good search capability — like Gmail’s — so you can keep years of messages on hand and retrieve them quickly. Gmail offers 2.9 gigabytes of storage free. It sells extra storage for prices ranging from $20 a year for six gigabytes to $500 a year for 250 gigabytes. Hotmail is in the process of boosting its storage to five gigabytes, free, and 10 gigabytes for $20 a year.

With Yahoo Mail, you can send attachments of up to 10 megabytes per message and 20 megabytes if you opt for a $20-a-year plan that also eliminates the annoying banner ads that litter the free version. Gmail offers attachments of up to 20 megabytes free. Hotmail allows 10 megabyte attachments and 20 megabytes under its $20-a-year plan, which also banishes ads. Gmail has no banner ads, just text ads that run alongside the emails and can’t be eliminated.

This new Yahoo Mail is gradually being rolled out in coming weeks. The company still plans to retain the older version of Yahoo Mail, now called Classic, for people who prefer it, or for those using browsers that are incompatible with the new version, such as Apple’s Safari.

The new Yahoo Mail allows you to do things that once were impossible in a Web-based email program. For instance, you can drag messages to new folders, or select a group of messages in the same way you would with a standard email program, to delete them or mark them as read or unread. Unlike in Gmail, when you right-click on a message you get a list of options that pertain to the mail program — like “Reply to Sender” — instead of options that pertain to the use of the browser — like “Add to Favorites.”

Also, Yahoo Mail features a very nice tabbed interface that Gmail and Hotmail lack. With this interface, which is separate from the browser’s own tabs, you could have your inbox in one tab, an instant-message or text-message conversation going on in another and a new email you are composing occupying yet another. You can move among these tabs without losing the content in any of them.

And like Hotmail but not Gmail, Yahoo Mail offers a preview pane, like Microsoft’s Outlook, so you can see the contents of an email without opening it. Gmail offers just a “snippet” of the message content. Unlike Gmail, which forces you to view your emails as bunched-up “conversations,” Yahoo Mail — like Hotmail — displays them as a standard email program does, sorting them by date, sender, subject or size.

So what are the downsides of Yahoo Mail?

Well, the biggest is probably that unless you pay for the $20-a-year premium plan, you can’t view your Yahoo mail account in a standard email program such as Outlook or Apple Mail. Gmail allows this free of charge. Hotmail allows it free in Outlook and in Windows Mail, though it will soon announce the capability for other email programs for premium members and, eventually, for free members as well.

Also, I found Yahoo Mail could sometimes be slow. When I created a new folder and tried to drag 200 emails into it, I was warned that I couldn’t do that because the new folder was “still being created.”

But overall, Yahoo did a really good job making its online mail program versatile, powerful and accessible.

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.

These technologies allow users to create highly personalized pages filled with just the information or tools they desire. If you’re interested in the car industry and college basketball, live in Toronto, love to view family photos and often use a calculator, you can fill your computer screen with small modules that display relevant information and necessary tools for all these interests. You won’t have to browse through the Web or launch a bunch of large programs.

These modules and miniapplications appear as small square or rectangular objects, with the content or functionality inside. You can arrange them as you like.

There are two broad categories of these personalized pages — those that appear as Web pages, and thus require you to be online to use them, and those that are on your local desktop. The latter don’t require an Internet connection, though some of their modules may work only if you’re online.

On the Web, the most familiar of these modular systems is My Yahoo, which allows you to combine page segments featuring Yahoo’s own news and information with segments containing syndicated feeds of headlines from other sites, often called RSS feeds. Others have launched similar pages. One longstanding competitor is Microsoft’s my.msn.com.

On the desktop, the best known miniapplication system is Apple’s Dashboard, which allows Macintosh users to install tiny programs called Widgets that perform searches, display photo slide shows, track stocks, play music, and more. Microsoft’s new Windows Vista operating system, out this week, has a comparable system called Sidebar.

Now, there’s a new free Web site that combines some of the best features of My Yahoo and Dashboard. It’s called Netvibes, it’s available at Netvibes.com, and it’s unusual because it’s from Paris, France — not Silicon Valley or Seattle.

Like My Yahoo’s system for displaying feeds from non-Yahoo sources, Netvibes allows you to fill your personal page with headlines from all over the Web. And like Apple’s Widgets, Netvibes’ modules are produced by a wide variety of users, who upload them and make them available free.

I’ve been a My Yahoo user for many years, mostly because it allows me to see a lot of information at a glance, and it’s mainly plain text so it loads fast. I also use Apple’s Widgets on my Macintosh machines. But I find myself using Netvibes more and more lately.

Netvibes isn’t the only new Web player in the personalized Web page space. A new entry called Pageflakes, run by an ex-Yahoo executive, promises a graphically richer approach than Netvibes that the company claims is easier for novices to customize. It’s at pageflakes.com.

And Yahoo is in the process of revamping My Yahoo to update its look and features. The details of the new design aren’t public yet.

Like My Yahoo, Netvibes is text-heavy and loads quickly. But depending on which module you use, it can have color and graphics.

A menu down the left-hand side of the screen lets you quickly add modules to Netvibes. Popular ones are listed in this menu, and you can browse or search for others by clicking a link called “Get more modules.” You can add feeds — headlines from regular Web sites that support them — by clicking “Add a feed.”

Among the modules you can add to your Netvibes page right from this menu, without navigating to any setup page, are weather forecasts, a notepad, a to-do list and calendar, and modules that perform searches for Web pages, blogs, pictures, videos and podcasts.

There are also email modules that will display your new messages from Gmail, Yahoo Mail, Hotmail, AOL Mail or any regular old email account you configure. Others display content from eBay, MySpace, Fox Sports and more.

To add an unlisted feed, you just navigate to a Web page that offers feeds and copy the Web address into Netvibes’ ”Add a feed” feature. Or you can place a button on the toolbar in the Firefox Web browser that will add a new feed with one click.

On my Netvibes page, I have modules that show the weather, my latest emails, the most popular stories from the Journal’s Web site, and top headlines from various technology and sports Web sites. I have colorful modules displaying photos from Flickr and other photo sites, and modules for video searches.

One nice feature of Netvibes is that you can set up automatically updated searches for terms that may appear in blogs all over the Web. For instance, you could create a module that will constantly show any new blog entries featuring, say, “Microsoft Vista” or “Apple iPhone.”

There are some downsides to Netvibes. Some of its modules seem aimed at techies, not mainstream users, and others are in French, though a version customized for American users is in the works.

But Netvibes — and competitors like Pageflakes — will give My Yahoo a run for its money. They provide an easy way to cut through the clutter of information that confronts us all.

• Email me at mossberg@wsj.com.

Like all other trends in technology, this one, sometimes called “Web 2.0,” is overhyped. It’s been happening quietly for years, but it’s a long way from replacing all the software you use.

Still, the biggest software company of all, Microsoft, has recently launched a major initiative to produce this kind of remote software. Its project, called Windows Live, is hardly unique. Google, Yahoo, America Online and many others are also offering new Web applications. But Microsoft’s Windows Live may be the biggest of these efforts.

Google Earth image of building housing Journal’s Washington bureau, top; the Microsoft image, below.

Why would Microsoft, or its rivals, want to make this switch? Well, theoretically at least, it allows them to write one program that can be used on multiple platforms — say, both Windows and Macintosh computers, or even cellphones. And it may allow them to sell subscriptions to their software, or to sell ads that could run inside the software. It will also make it easier to update programs, and to construct programs that can synchronize data among multiple PCs or users.

Some of this stuff would clearly benefit consumers. You could fire up your favorite program from any Internet-connected device, just as you can log onto Web-based email now from any PC. And you wouldn’t have to download or install updates.

But other features of this new world, like ads in software, may be annoying to many consumers. In the world of Web 2.0, people without fast, costly broadband connections would be able to do less and less with their computers.

To get an early look at this new approach, I’ve been poking around in Windows Live, which is a grab bag of mostly free programs. Some, like Windows Live Messenger and Windows Live Mail, are renamed and revamped parts of the company’s MSN online service. Others, like the OneCare Live security service, are new ideas.

All of these programs are in the testing phase, and this column isn’t intended to be a full review of any of them. But here’s a quick, early look at three components of Windows Live.

Windows Live Local: This is a local search and mapping service, complete with aerial photos of cities and towns. Built on an earlier Microsoft project called Virtual Earth, it’s intended to compete with the local search and mapping features of Google and Yahoo. It’s also a competitor to Google Earth, a satellite mapping service that requires an installed program to use. By contrast, Windows Live Local works entirely from a Web browser, and it runs in both Internet Explorer and Firefox, and on both Windows and Macs.

The most startling feature of Windows Live Local is that it can display real 3D aerial images of buildings and houses in many U.S. cities and suburbs. These pictures don’t merely display the roofs of buildings, as Google’s do, but their sides. The difference is enormous. Instead of puzzling over roof shapes, you can easily identify buildings and get a much better feel for neighborhoods.

In its current form, however, Live Local has limitations. For large swaths of the country, 3D photos, which Microsoft calls “Bird’s Eye” views, aren’t available. In Bird’s Eye mode, panning and zooming are clumsy and limited, street names aren’t overlaid on the images, and there’s no easy way to save them. But it’s still a huge step forward. It’s at local.live.com.

Windows Live Mail: This is a massive upgrade of Microsoft’s popular free Hotmail email service. It is simultaneously much cleaner looking and more sophisticated. There’s now a preview pane to the right of the message list, just as in Outlook. Messages can be dragged into folders. When you right click on something, useful email options appear instead of just browser commands.

The new mail program auto-completes addresses and saves sent messages. There are various new security and editing features. Overall, it works much more like Outlook or Outlook Express, though currently many features don’t work on the Mac or Firefox. It will also offer two gigabytes of free storage. People with current Hotmail addresses will be able to keep them, but new addresses will look like “johndoe@livemail.com.” It will be available at mail.live.com soon.

Windows Live OneCare: This is a complete, managed security service, for Windows only, that will be available by paid subscription. The goal is to keep a computer constantly protected and updated with little or no intervention from the user. It does require locally installed software, but it’s managed remotely by Microsoft, the same way a corporate IT department remotely manages the security of all the computers at a company.

OneCare, which I will review in full later, also has features to keep a computer tuned up and backed up. As of now, it lacks a crucial feature: antispyware capability. But that is planned. It’s at onecare.com.

• Email me at mossberg@wsj.com.