ChordIQ - Learn notes, chords, sight reading, perfect pitch and more.
Synthesia - A fun way to learn how to play the piano.
7Pad Scales and chords - Music instrument and assistant for playing scales and chords.
Playground Sessions - Online piano learning game.
Scale Heaven - Browse and play any scale/chord, chord progression.
Piano From Above - Piano From Above is a program that turns learning the piano into a videogame.