tonestro - Practice & improve on your wind instrument while having fun
Flowkey - The easiest way to learn piano with your iPhone or iPad
Flat - Online collaborative music score and tab editor, accessible from any device
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Transposr - A free and simple way to transpose your sheet music or MP3.
Simply Piano - Fast and fun way to learn piano