I got bored today, so I decided to try and find all of the cool and useful Firefox extensions that existed. This is what I ended up installing:

• Google Browser Sync - Store all of your settings and bookmarks so you can share them amongst multiple computers. They can track me all they want with this, I think it is cool as hell :)
• adblock with FilterSet.G - Has worked great for me for weeks now and I don't notice any ads most of the time :)
• customizegoogle - Lots of very cool tweaks for your Google searchs and all of the other offerings from Google
• dmextension - Some nice little tweaks for the download window (make it into its own tab, for example)
• easyGestures - A lot easier to use than any of the other attempts at mouse "gestures", imho.
• PDFdownload - Lets you tweak how you want to handle PDF files.
• Smoothwheel - Makes scrolling with the mouse wheel nice and smooth. Also makes it feel more accurate, in my opinion.
• Stop or Reload - Makes the stop and reload button into one button, since you can only really do one operation at a time :)
• Tab Mix Plus - Lots of tab options, like adding progress bars, locking, etc

I think they are all cool. I'll probably remove a few after they start to piss me off, but I think most of them are useful, or don't really make the browsing experience any worse. Anyone else have recommendations for some good extensions?