FEBE (Firefox Environment Backup Extension) allows you to quickly and easily backup your Firefox extensions. In fact, it goes beyond just backing up -- It will actually rebuild your extensions individually into installable .xpi files.
A productive way to organize, read and share the content of your favorite feeds, blogs and news sites. Feedly offers a seamless transition from Google Reader.
— Open web pages saved with Internet Explorer or other browsers (MHT)
— Save many tabs, video and audio reliably, in a single ZIP file (MAFF)
— Return to the original site you saved a page from, and more!
Adds the ability to create and edit entries in the password manager.
StumbleUpon is the easiest way to discover new and interesting photos, videos, web pages and more, recommended by a community of experts. Tell us what you are interested in and we recommend page after page of amazing stuff you’d never expect to see.
Integrate your Facebook life into your browser...
Skips unnecessary pages on sites like Rapidshare, 4Shared, zShare, Mediafire, and more. Try it out, or watch a demo at http://www.skipscreen.com
Why click through ad-laden pages and wait for countdowns when your computer can do it for you
FoxClocks shows times around the world - or just your local time - at the bottom of your browser. It deals with daylight saving time so you don't have to.
Help make Firefox better. The Add-on Compatibility Reporter enables you to report if the Firefox add-ons that you're using are working properly.
Customize application menus:
Rearrange or remove menuitems from the main context menu (right-click menu) and main menubar (File Edit View etc.)
Automatically find user scripts on Userscripts.org (requires Greasemonkey or Scriptish)
If you aren't concerned about someone looking over your shoulder and stealing your passwords, why hassle with those obfuscated password fields, where you never know whether you typed your 30 character code correctly or not...
Shareaholic is the easiest way to share interesting links using Facebook, Twitter, Google Mail, Reader, Bookmarks, Evernote, Bitly, StumbleUpon, and more... from one simple ALL-IN-ONE add-on. This is the ultimate tool for the link sharing addict!