I have a bunch of mics in my bathroom; I record myself taking a **** everytime I go and I listen to those recordings when I play poker, usually. When I get sick of that I listen to old REM live bootlegs, or a random cycle of old Pantera songs (studio cuts).
Or hearing great lines such as "This is manslaughter. I'm so far ahead of your time, I'm married to granddaughter's grandaughter. http://www.youtube.com/watch?v=zhDUS9uybf0
Sort of joking - Listen to anything from Atreyu, Enter Shikari, Bullet for my valentine to BIG L to Biggie, to Rakim, Nas, Tech N9ne. The I settle down for some Radio 1 covers in the live lounge: My favourite
I listen to Pandora Radio.. One minute I might be in the mood for Bob Dylan, or if I'm getting sleepy, some hard house.. I listen to it all, it just depends on my mood..
I think you should pick something that makes you comfortable. If heavy metal is in your comfort zone then go for it. The whole point is to keep you even keel throughout the session. Recently I started using last.fm radio over pandora. Lots of instrumental stuff suits me well because I find lyrics can be pretty distracting while playing. Also, this is probably the wrong forum and there are threads about this afaik.
i listen to Xmchill on direct tv or xm radio obv. when away from home i have an app called stream furious on my tmobile g1 that has a station called chroma alternative/electro that is the nuts. if both those fail try putting royksopp in pandora.
Haven't listened to it in a while but relaxation music is pretty good. Like just natural sounds, not the hippy stuff. Anything without the sound of crickets is great. Which reminds me I need to download some whale music and give it a try. Rainforests, thunderstorms and the sea are all very good.