AniMusic is pretty cool! Check out the Video Clips. :)

"Animusic is computer animated music . It's unique, captivating, and not that infrequently causes jaws to drop. The animations are created with computers utilizing a process similar to that of movies like Shrek and Finding Nemo (although we add our own "secret sauce" that allows musical instruments to magically animate themselves)."

(Thanks, Kaveh)