If I'm doing more tedious things like linework or toning comics (and sometimes even coloring), I tend to lean towards listening to podcasts or audiobooks (or
podcast audiobooks), or having the TV on. It gives me something else to concentrate on while I'm drawing so my mind doesn't wander off and go "hey, I wonder what's going on on the internet" and make me waste an hour checking Deviantart, Facebook, etc.
If I'm sketching or working on something particularly...inspired, I go with whatever suits the mood, usually. My playlist contains everything from country to punk rock and just about everything in between. Hah, I actually have some lists set up with all music that fits a certain mood/situation. Like one labeled "Fight Songs" for drawing battle scenes. It's mostly fast, angry...fight-y...sounding music. Yeah. Something like that.
(Actually, there's two of those. One in English and one in Japanese XD) And sometimes I just go through phases where I'll be addicted to one type of music and it'll influence everything I draw.
Like, lately, I find myself rather attached to pop rock/pop punk. Ahaha. That's producing some interesting stuff.