Generally I agree with higher energy music like Eminem's Lose Yourself but I agree with Meg on "Against Me!" if you're in a younger generation.
For some other stuff I like that is pretty goofy I like Stan Bush's songs from the Transformer's soundtrack. That would be "Dare" and "The Touch." They are pretty much cheesy encouragement sayings put to music.
Also, anything that stirs up any sort of emotions. Just take whatever emotion it is and focus it on motivating yourself for the task at hand.