Extensions by Weekly Downloads
Xmarks Sync Requires Restart
Xmarks is the #1 bookmarking and open tab add-on. Keep your bookmarks, and open tabs backed up and synchronized across computers and browsers. Mobile phones with Premium access. Utilize LastPass to sync passwords!
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
Lightbeam for Firefox Featured
Lightbeam is a Firefox add-on that enables you to see the first and third party sites you interact with on the Web. Using interactive visualizations, Lightbeam shows you the relationships between these third parties and the sites you visit.
FireGestures Requires Restart Featured
A customizable mouse gestures extension which enables to execute various commands and user scripts with six types of gestures.
Easily download most popular video formats.
Theme Font & Size Changer Featured
Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.
This extension adds a button to download every Facebook Video.
Shut down the lights on YouTube.
Quickly toggle between blocking all pop-up windows and allowing some pop-ups
Torrent Tornado Requires Restart Featured
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
Restrict Proxy by Private Windows, Tabs and Domain List
Hide Your IP Address and Unblock Websites for Free with the Hide My IP proxy and VPN IP network. Thousands of IPs around the world to choose from. Access your favorite streaming sites by changing your IP location. No ads or limitations.
A very lite YouTube downloader (FLV, WebM, 3GP, and MP4)
Replace video player with Firefox native video player
Selenium IDE Button Requires Restart
Just one simple toolbar button to open Selenium IDE. You need to have installed Selenium IDE: http://seleniumhq.org/projects/ide/
Media Converter and Muxer is an easy to use video and audio converter and muxer.
Personas (now known as lightweight themes) are free, easy-to-install "skins" for Firefox. Personas Plus extends that built-in functionality to give you even more control and easier access to new, popular, and your own favorite themes.
Click&Clean Requires Restart
The quick and easy way to delete your browsing history, erase all temporary internet files, remove downloaded files history, cookies, Flash LSO, typed URLs. Allows to delete private data when Firefox closes. Supported ext. tools like CCleaner.