In RPGs, I'm the wizard. I like playing utility wizards more than blasty ones, where I can control the battlefield, curse or bless at will, and control peoples' brains. In EverQuest, I was a happy enchanter.
In FPSs... well, I don't play them so often, and my aim sucks, so I'm most effective when causing damage over a huge area. I like flamethrowers, grenades, acid grenades, grenade launchers, rocket launchers, spray bottles filled with lye, you get the idea.
I am also, more often than not, the only girl on the battlefield.