Synthesia - A fun way to learn how to play the piano.
Virtual MIDI Piano Keyboard - Virtual MIDI Piano Keyboard is a MIDI events generator and receiver.
Piano From Above - Piano From Above is a program that turns learning the piano into a videogame.
Playground Sessions - Online piano learning game.
Touch Pianist - Play piano like a pro without playing piano.
Linthesia - Linthesia is a game. A game of playing music! You only need a MIDI file