I only have one warning for you guys.. Don't overload on the extensions or themes.. Themes are more okay tho.. Extensions can get nasty however... Keep only what you like and use, remove the rest.. Also remember to keep extensions Updated! The auto updater function does NOT always work, pay the programmers site a visit on a monthly basis just to be sure..
ATM I'm using: noia 2.0 eXtreme w/ Mouse Gestures, ieview (for pesky sites), Dictionary Search, Googlebar and Forecast Fox.. The only extension that has some problems still with Firefox v1 is Mouse Gestures..