Firefox - Have it your way!
Lesliefranke.com has a great list of great Firefox Extensions. Most of which I run on my install daily. I’d have to agree that Tab Mix Plus and Adblock Plus rank as number 1 and 2 on my list of extensions. SpellBound and PDF Download are invaluable too. Gmail Manager is great if you have multiple gmail accounts (like most podcasters do). BugMeNot is very good at getting you into popular websites that you don’t want to hand over your personal info to access. Web Developer is most likely the most actively used extension that I use. I did a EverythingTech.tv podcast episode using it.
Take a look at the list: http://lesliefranke.com/files/firefoxyourway/ and hopefully you’ll find some new extensions to better your Firefox experience.