tonestro - Practice & improve on your wind instrument while having fun
AMPLI.FI - Live online music community. Twitch for tunes.
Violin by Trala - Violin by Trala is a music learning app that is designed specifically for Violin users.
Krue - Twitch for music: live streams from amazing musicians
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Soundscape - Sync your music with the open source community