For some reason good music[1] with vocals that I haven't heard to death add a sort-of distraction when I'm working so I choose to listen to music that I've heard enough to have memorized the vocals or music without vocals at all. Since it gets annoying to listen to songs I've memorized, I'll pick acoustic or unique covers of that music (I've grown fond of odd piano covers - I found five tracks that are piano-only versions of My Chemical Romance songs -- a band who's music I generally don't enjoy but when done in piano, it's just ... oddly interesting).
When I'm in an intense bit of code, rapidly writing implementation, I like to pop in Progressive Rock of any kind, the longer the track the better. I'll often pick something by Dream Theater, though sometimes the metal-ish sound is a little much for me depending on my mood.
[1] As in, music I enjoy listening to which is usually 70s rock and alternative from 1995-2010. That's not to imply that this is a universal definition of "good music", only that it's what I enjoy listening to.