Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
The first and only download manager/accelerator built inside Firefox!
The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
Protect your privacy. See who's tracking your web browsing and block them with Ghostery.
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Orkut, and many, many other sites. You can even customize Firefox and other programs themselves.
Find out which websites you can trust. WOT adds intuitive traffic light-style icons next to search results and URLs to help you make informed decisions about whether to visit a site or not.
Collector's Note for safer browsing..
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
This add-on is a downloader that lets you easily download videos and music from sites like Youtube, Facebook, Metacafe, Dailymotion, Break, VKontakte, DivShare and music for example from SoundCloud, Grooveshark and from many other sites...
Never be annoyed by a Flash animation again! Blocks Flash so it won't get in your way, but if you want to see it, just click on...
Collector's Note to block flash in any website & Just 1 click to unblocked it if you want to see the flash
LastPass, an award-winning password manager, saves your passwords and gives you secure access from every computer and mobile device.
Tab Mix Plus enhances Firefox's tab browsing capabilities. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager.
The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.