Flowkey - The easiest way to learn piano with your iPhone or iPad
tonestro - Practice & improve on your wind instrument while having fun
alphaTab - alphaTab is a cross platform music notation and guitar tablature rendering library.
Piano2Notes - Piano2Notes is a web application and mobile that transcribes your piano tune into a digital word document.
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Yousician - Learn to play music at home, at your own pace