When I first started my first serious relationship I made the mistake of telling my girlfriend how much I had enjoyed Dr Sam Beckett getting it on with the psychic with Foreigner's "I Want To Know What Love Is" playing in the background. During one of our own liasons about three months into the relationship I made the mistake of leaving my Winamp (that's right) playing on shuffle. We were just getting to the point where penetration was imminent, when that very song started playing, and she pissed herself laughing. If you've never fucked a girl while she's laughing uncontrollably and unable to stop, I highly recommend it. I don't actually think I've ever put music on for sex other than to conceal the sounds from people in other rooms, I much prefer listening to the moaning/heavy breathing/words coming out of my victim partner.
Oh (cough) ummm, I mean, some speed metal or something.