Four-seamer, 2-seamer, change-up, curveball, slider, split-finger, forkball, knuckleball. I ran into this 1-page pdf file from the Seattle Post-Intelligencer from a few years back. You get photos of exactly how to grip the ball, and a description and diagram of how to throw it and what each pitch does. It definitely cleared up some questions for me ... maybe for you, too?

http://seattlepi.nwsource.com/baseball/pdf/pitchingpage.pdf