AMPLI.FI - Live online music community. Twitch for tunes.
Chordify - Chordify turns any music or song (YouTube, Deezer, SoundCloud, MP3) into chords.
Bandlab - Capture, nurture, and collaborate on song ideas in the cloud
muted.io - A magical collection of interactive music theory tools & visual reference pages for musicians and music producers
Soundstripe for Twitch - Free music for Twitch streamers
soundrop - Soundrop is an app that allows you to create your own personalized sound track to keep you focused or relax.