Post your favorite Firefox extenstion?
 

Mine has got to be "NeedleSearch"

Its a drop down menu like the standard google one but add custom things
I got it configured for all this

Google
Google Images
Ebay
Board Tracker
GFY
Whois.sc
Alexia
Currancy Exchange
Downloads.com
Hotscripts
Overture
web.archive.org
Dictionary
Thesaurus
IP Lookup
Spell Check

You can also have it Search within page and Highlight ect...

Beat that :thumbsup