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.
Bandlab - Capture, nurture, and collaborate on song ideas in the cloud
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Blattarco - Creative self-developement for musicians of all level.