tonestro - Practice & improve on your wind instrument while having fun
Metronaut - An app to help you play classical music
Piano2Notes - Piano2Notes is a web application and mobile that transcribes your piano tune into a digital word document.
Flat for Education - The best way to teach music to your students
Simply Piano - Fast and fun way to learn piano
Scribd Sheet Music - All the sheet music, books and comics you want for $9/month