Ok, these are absolutely amazing. This comes from Japan, of course Japan, because people seem to have an abundance of free time there. A mysterious fellow, "Jinja", made these music visualizations by basically showing the piano keyroll of the midi of the songs. They are absolutely freaking amazing. My favorites are the Final Fantasy IV one and the ending of the Medley. Thanks for the link Dherman! Watch and behold:
Final Fantasy IV
Medley (Go Gradius!)
Super Mario
Megaman 2 Dr. Wily Stage 1 (OKKUSENMAN!!!!)
Kirby