I used to play at my old gf's house, and since she had two daughters there was plenty of background noise which gave me something to concentrate through. She and I split up--largely because I was spending more time on her computer than on her--and I started playing in my office after work, which I first got used to and now prefer. The downside to playing in silence is it doesn't really prepare you for live play, but then one of my favorite aspects of online poker is how anti-social it can be.
I prefer playing with a song in my head versus music in the background. I've experimented with different types of music and even seal noises, but I seem to play better after the cd runs out. When I've played my best, at the end of the tourney I turn around and am surprised to find the cd player that I'd forgotten about.
What helps the most are visual aids. Before the start of a tourney I'll find a picture--usually a painting, a photo of an animal, or a childhood pic of an old friend--and I'll relax gazing at it. During the tourney I'll keep the photo available on a tab on the computer, and if I ever need a kick in the pants or to calm down, I'll click back and look at it and regroup. I can't begin to explain how helpful doing that has been. I completely understand why some players take photos with them when they play live.