Awesome question.
I have a page about the best workout music
Best Exercise Music
But I think it's time to do a top 5 list about the best workout music!
Right now I have Copone n Noriega - War Report
8 Ball - Lost Double CD - one of the best Hip hip albums ever (not that great for working out though)
Offspring - Used to listen to them in high school
Rob Zombie- Super Beast is one of my favorites
Slumdog Millionaire soundtrack
Not the best workout music but that's what's in the deck for me...