Firefox allows me to add things to it, some I can't be without now, I know Firefox got it's faults, like being slow to start up, but I think it is the best browser out there at the moment.
Amen to that -- I don't know of any other browser where you can add a feature to translate Japanese text just by hovering the cursor over it (though obviously you still need some knowledge to be able to piece it together, which fortunately I do

). Until they have something similar available for another broswer, I'm a Firefox man.
Though I'd be a 64-bit Firefox man if stupid Adobe would hurry up and make a 64-bit version of Flash, so I wouldn't have to do without YouTube. I thought 3.5 would be the ticket, what with its built-in media-playing feature, but the 64-bit version of the release candidate doesn't do Flash