I was going to choose a source from a modern indie game with music from a guy I've been chatting with (and I should've tried to get him to join the compo!), but unfortunately that wasn't possible :(
Instead I choose Level Theme from the great game Tyrian:
Deadline is Monday September 26th, 10:59 AM ThaSauce Time. Check my Ocremix signature for the exact time left.
Start: on 9/16/11
Deadline: on 9/26/11
Voting: on 9/28/11