Drum and Bass (classic stuff RAM Trilogy, ShyFX, Dillinja, Aphrodite etc) IDM (Square Pusher, Aphex Twin) or Glitch (Dntel). Don't do Dubstep, although I'll refrain from bashing it

Sometimes classical, more often modern piano compositions, pianists such as Yiruma or Marika Takeuchi are my favorites atm.

But specifically whilst coding, more than anything else; I'm listening to my archive of classic game tunes! High voltage sid collection, module music from the Amiga and the occasional game tune cover done by a band.

But nothing with lyrics, I'm a life long musician so I'm picking out chords, structure etc in a piece of music and hearing words as well is too much to process whilst concentrating on coding. At least I think that's the reason as I don't have an issue coding whilst listening to people speaking on the Radio etc