I usually just listen to any of the 100+ songs I have in my folder... Depending on the picture I'm drawing. If I draw fanart, then I usually play its official soundtrack, the song depending on the type of drawing; if it's sad, I play its sad OSTs, if it's badass and actiony, I play their battle tracks or OP songs, etc.
Or I can just play any song, as long as it fits what I'm drawing.
On the other hand, most of the times I drew my comic, I was endlessly looping my Linkin Park playlist...