tonestro - Practice & improve on your wind instrument while having fun
Gnoosic - Even if you don't know what you are looking for - gnod will find it.
Piano2Notes - Piano2Notes is a web application and mobile that transcribes your piano tune into a digital word document.
Musicroamer - A visual Pandora for discovering new music
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
TasteDive - TasteDive recommends similar music (musicians, bands), movies, TV shows, books, authors and games, based on what you like.