While everyone is giving their favorites I thought I would throw mine in. Two sites -- pandora.com and coffitivity.com On pandora -- their baroque classical st

While everyone is giving their favorites I thought I would throw mine in. Two sites -- pandora.com and coffitivity.com On pandora -- their baroque classical station On coffitivity -- University undertones. You have to fiddle with the volumes a bit to get them balanced, but once you do it is a great passive sound for concentration and focus. Also a good one that I picked up from my college roommate -- drum and bass techno. Anything with lyrics gets me thinking about the lyrics.