Fuck censored NIN.
"Blood Rave" by The Crystal Method has a great baseline, but isn't rock or roll.
"Ratamahatta" by Sepultura is pretty kickin'
Pig Destroyer's "Piss Angel" might be a good choice,way over the top, and if she goes into the ring/cage second, it would scare the shit out of her opponent.
Of course, if I was fighting, I'd pick "Angel of Death". Of course.