I posted this list in a thread with a similar topic:
Metal/Rock
Marilyn Manson - none of his new crap, get the best of album (lest we forget), Drowning pool - first album, slipknot, dope, AC/DC, NIN, sick puppies, apocalyptica, the cult, filter, korn, limp bizkit, linkin park, My chemical romance, sevendust, system of a down, Monster Magnet, The White Strips
Techno/dance
BT,David Guetta, DJ Tiesto, Fatboy slim, Hybrid, Mark Ronson, Paul Okenfold, Pendulum, chemical brothers, Inner Party System
These are some of the artist I have on my workout playlist. I find that when lifting weights, I tend to listen to the harder music (gets me psyched) but when doing cardio I like the techno (constant beat to pace myself).
Whether it be only 1 song or 50 songs from an artist, I only put the songs that truely inspire and pump me up on my playlist.