Years ago I started an interesting musical experiment.
I had noticed that when I'm working, if I listen to one style non-stop my brain gets very 'muddy' and often builds up a nice solid headache.
I'd been using pandora and sticking to a single genre (psy-trance / techno / electronica) and while it was good it's repetitive nature (don't laugh) were part of what was leading to my muddy-headed feeling.
I decided to start throwing all sorts of random things into my "Messy Mix". It is pretty simple: * Put in new music I find that I like by artists. * Thumb up songs that I like. * Never thumb down anything. (this is harder than it sounds)
And now I have this mix that ranges all over the place and leaves my head feeling nicely refreshed even after hours of listening to it while I am working.