Destroy the Web
Turn any webpage into a shoot-em up video game.With a pulse pounding soundtrack and high scores for every web page, Destroy the Web is a fun way to take a little break during the day.
Shareaholic | share with Google, Facebook and more
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!
Personas Plus
Personas 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 Personas.
Stylish
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.