Usually industrial, electronic or trance. I do enjoy listening to ambient chill a lot when I am playing...keeps me in the "zone."Something like this from Solar Fields:http://youtu.be/mfonpcWWWVo
Mozart piano concerto no.20 and n0.24
Classical. Doesn't matter which period. Just Classical.
For speed games:Metal Gear Solid - Escapehttps://www.youtube.com/watch?v=DojV0tM-dR4The melody is a good fit for the typical tension of speed chess, I reckon.For slower games: if I can get away with listening to music while playing (not always possible in rated tournaments, for example) whatever I normally listen to.
'If I Could Have Her Tonight' (Neil Young from the self-titled Neil Young album)
. . . meaning, of course, the enemy's queen!--if I could have HER tonite!
Classical or trance. There is no two ways about it.
Unless of course you have poor taste!