Hum - Songwriting for iPhone
AIVA - The AI composing emotional soundtrack music
Songcraft.io - A platform for songwriters to write, organize & collaborate.
WaveBots Editor - Procedural music and sound maker that exports to Wav, MIDI, GoatTracker and much more.
RiffShare - Write down a musical riff, send to band members, collaborate
WolframTones - Listen to what I just found in the WolframTones music universe