Firefox Add-ons - what do you use?

[Tamur]

Lots of great options, I'm interested to see what others use.

Here's my list for Firefox 3 (that haven't been mentioned already):

PicLens - very slick interface to picture archives
Web Developer - great coverage of the entire web coding arena
IE Tab - switches page view to and from the IE engine
Flashblock - the best addon ever
Forecastfox - handy, nicely configurable weather

Firefox 2 addons I really, really miss and still use FF2 for:

Firebug - step through JavaScript, invaluable
Fire FTP - full FTP client in a browser window