Al's list of Firefox Extensions you should be using.

• Adblock Plus
  Because it blocks those obnoxious banner ads! The 'Plus' is because it subscribes to an ever updating list of sites to block.
• Fire Gestures
  Adds mouse gesture functionality allowing you to do just about anything browser related with a flick of the wrist.
• Web Developer Toolbar
  If you do any sort of web development at all, this is a must have. Allows you to slice and dice measure and inspect every aspect of a webpage.
• Google Toolbar
  Quick and easy access to all of Google's applications. Also lets you set Gmail as your default email application.
• Compact Menu 2
  Turns your entire menubar into 1 button. Saves some screen real-estate.
• Tree Style Tab
  If you deal with a lot of open tabs, this addon arranges them in a much more easily navigable manner than the standard "row along the top".