I downloaded some free music this week - a 13 minute track of electronic trance music - and listened to it for a few days solidly while working. That's unusual for me.
It's some remixed music from the Geometry Wars games (old-school Robotron-style shoot-em-ups), from UK games company Bizarre Creations. It's good music to work to; instrumental, a little retro.
See this article on where to get it, if you're interested:
C&VG article