I loved reading this thread because there were a few extensions I hadn't heard about until now.

I'm definitely downloading minimize to try, both at home and at work!

My favorites are pretty much already listed, except a couple. I'll be redundant and list 'em again, though.

NoScript - one of the best darn extensions around.
AdBlock Plus - better than regular ol' adblock, in my opinion.
Colourful Tabs - just to add color to the many, many tabs I always have open.
GMail Manager - can't live without this one!
StumbleUpon - assuming y'all know what StumbleUpon is, this is just a fun one to have!
IE View Lite - used only when I'm forced to examine a page in IE.