1. ColorfulTabs: Turn your installation of Firefox into an artistic statement with ColorfulTabs. It makes every tab you open a different color, so they're easier to tell apart at a glance—and a major part of a more vibrant, attractive Firefox window.
2. Cooliris: Surfing the Web can be informative and fun, but even the most dynamic Web sites look pretty much the same. Not anymore. Install Cooliris to view search results on sites like Google, YouTube, and Flickr, and photos from Facebook, Picasa, and your PC as an infinity-spanning 3D wall of windows.
3. Echofon: Love Twitter, but hate having it open on your PC all day or running a separate program to follow your friends? Echofon sends notifications of your followees' updates right to an icon in your status bar, so you can click and see them anytime you want, no matter what you're doing. Echofon supports multiple accounts and direct messages, too.
4. ForecastFox: Never again be caught without your umbrella or sunglasses just because you forgot to check for clouds before you left the house. Install ForecastFox to view AccuWeather.com weather forecasts from all over the country and the world right in the toolbars section of your browser window.
5. GooglePedia: The wealth of information available in Wikipedia is staggering, but it can be a pain to head over to it anytime you want to look up one little thing. GooglePedia solves this problem by displaying a related Wikipedia article along with your Google search results. The links in the Wikipedia article will automatically start new Google searches using those terms.
6. LastPass Password Manager: Keeping your various online log-ins secure is hard enough; remembering them all can be even bigger challenge. That's what's great about LastPass, which can keep track of your usernames and passwords for you, so you only need to remember a single log-in (the one you use for LastPass). It also fills in forms for you, helps you manage data across multiple computers, and can help you track down passwords you may have lost on your computer. (Check out our full review of LastPass.)
7. Morning Coffee: It happens to all of us: We want to check our favorite Web sites in the early mornings before work, but while we're still groggy from sleep we can't quite get the mouse or keyboard to work the right way. Morning Coffee saves you the trouble by letting you organize Web sites by day and open all that day's sites when you fire up Firefox. This addon could save you so much time, maybe you can catch a few more Zs before you log on.
8. StumbleUpon: The Web can be overwhelming and finding really interesting sites next to impossible. StumbleUpon can help: Click the "Stumble" button on the toolbar it adds to be taken to a site. If you like where you end up, click the "I like it!" button; if you don't, click the thumbs-down button. StumbleUpon learns from your answers (and those of millions of other users) to serve you better sites in the future.
9. Tab Mix Plus: Tired of the same old boring tabs? Load up Tab Mix Plus, and start duplicating them, closing multiple tabs at once, controlling when and why they open, and much more. You'll never go back to traditional tabs again.
10. Xmarks: If you're a compulsive bookmarker and you regularly use multiple PCs, Xmarks could save you a lot of frustration. It can back up and synchronize your bookmarks and passwords, and even can help you discover new sites you might be interested in (based on what other users are bookmarking).
Thanks to http://www.pcmag.com for the info …