Check out the Andy Marte entrance music that will soon be sweeping Cleveland (link stolen from Kevin Goldstein's latest Future Shock column at Baseball Prospectus). I dare you to listen just once...
I can't find it online, but Blender magazine had a cool article about entrance music about a year ago.
So let's say you get the call. You're finally in the bigs now. The Jacobs Field PA announcer calls your name. You stride from the on-deck circle to the batter's box.