I presently use:
Dictionary search
Translate ( which is the one I used for the russian- it uses babel fish (i think) automatically)
Image Zoom ( jrv hooked a nicca up with that one- its good, you can zoom any pic with a right click)
Gmail notifier


The thing is since the latest update of firefox I haven't been able to use the auto updater to update all my versions of these extensions dude. Maybe Jrv and Jamesn will holla with some more cool extensions because they are the ones who are the firefox experts.