Over the past 2 weeks, I've been listening to Neil Young, Negativland, Alice in Chains, the Beatles, Conan Soundreack, Pink Floyd, Tool, a string quartet playing Tool, and the radio (either a classic rock station or news/talk)
Since I am playing bass in a production of "Godspell" I have been listening to it every day. Also, since I am teaching Debussy's La Mer, world music and Robert W. Smith's The Odyssey, I have listened to a great deal of that lately as well. Also, as I am putting together a Duke Ellington marching show for my band for next year, that has been listened to a bit too.
Other than that:
Boston Brass
Howie Day
The Devlins
Old Crow Medicine Show
Mutual Admiration Society
Death Cab for Cutie
Styx w/ orchestra
Bruce Springsteen
Hotel, by Moby (mainly the ambient disc -- great for late car rides home)
With Teeth, NIN
Ten, Pearl Jam
Audioslave, Audioslave
The last two spend a lot of time in my car stereo.
As for music during D&D games, I don't play any in the background. I have been considering it lately, though, because the GM for the Stargate game I'm in uses music and it works out really well.