any sound that relaxes you and engages whatever little brain cells are not entirely necessary for the task at hand is great to use. it makes concentration a whole lot easier.
personally, i turn on a baseball game, especially a spring training afternoon game. if it's on the TV, the commentators will tell you when you have to look, otherwise the nature of the game means that good commentators can convey both the action and the atmosphere without interrupting what you're doing. another good choice is the endless repeats of "How It's Made" on the Discovery and Science channels.