I used alot of these when I walked and I think they are very motivational, I don't want to stop till I have heard all of them. This week my line up is:

Starry Eyed Suprise - Oakenfold
Eye of the Tiger - (Always motivating!!!)
Get up/Say what - Not sure who this is, found it at Walmart.com $.88 per download
Shut Up - Black Eyed Peas
Smells Like Funk - Black Eyed Peas
Pump It - Black Eyed Peas
My Humps - black eyed Peas
Shining Star - Earth Wind and FIre
Fantasy - Earth wind and fire
Milkshake - Kelis Tasty
Little Bird - Annie Lennox - Dance Vault Mixes

Also the Grey's Anatomy soundtrack is pretty good too...

Just my $.02 worth