When I'm coding I either use; www.getworkdonemusic.com or www.mynoise.net. GWD is just a soundcloud interface with some fast vocal-free techno beats, so it pumps me up while not interrupting my focus. I get frustrated with it because it breaks a LOT. I'd say ever 5 or 6 songs it will finish playing a song and fail to load the next which is absolutely attention killing when you're in the middle of a creative rush.

Mynoise.net on the other hand is absolutely incredible but it's ambient sounds. The guy who runs it is a sound engineer and he updates the site frequently with new sounds. It's seriously great. Ive donated multiple times. He now has an iPhone app as well.

I absolutely love his binaural beats, airplane cabin, sail boat noise machines.