vimperator aka pentadactyl. works really well and if you press the alt key you get the "standard" menu back. it increases screen real-estate, and i love it. it's by no means perfect but i won't go back to standard key bindings in firefox... ever. yes i also have 200-300 tabs open in firefox, and maintain them there for months at a time. firefox continues to eat memory (i got a laptop with 16 GB of RAM just to cope with how insane firefox gets) so a restart is necessary on a regular basis... that's done inside pentadactyl with ":restart".