Trick Daddy- Let's Go!...beat is crazy...this is the ultimate pump up beat. played at stadiums everywhere.
Daddy Yankee- Gasolina...umm...it just works for some reason.
Elephant Man- Pon De River Pon De Bank...this guy is absolutely nuts. He's on something, but with that flow and that beat, it's gotta pump you up.
2Pac- Hit 'Em Up...thug song...gets you ready for battle.
Eminem's "Lose Yourself" seems to work for a lot of people. If you want something slower to meditate, try R. Kelly's "The World's Greatest."
Personally, I like to slow down a bit instead of pump myself up with loud banging music. The more sentimental stuff like 2Pac's "Dear Mama," Eminem's "Sing for the Moment" work for me.
Edit: I also like the NWA's F Tha Police.