I second Apples in stereo! Love them! I also like Cursor Miner, CSS, and Chromeo for working out to. You could also try Tiga and Felix Da Housecat if you like doing high impact stuff and like a strong baseline to work with.
Pussycat Dolls are good! Britney, Justin, Calvin Harris, 3oh!3, Anything that is going to make you move faster, feel good and keep you going! I love anything upbeat, pop-py. Go through your music list/itunes, and make a playlist Good luck!xxxxx