Jan 24th 2008 7:37PM I'd rather gouge my eyes out with a spork than listen to metal (of *any* variety) while playing. I tend to turn off the game music and usually the sounds, too, while grinding. During those times, I listen to anything from the fore-mentioned Mike Oldfield to Conjure One to BT to various dance/trance artists to movie soundtracks.
The musical selection varies with my mood and the content I'm experiencing at the moment.
Usually, during instancing, I'll put on non-obtrusive (read: non-distracting) music low so I can hear my party-mates on voice comms.