Keezy Drummer - Make a beat in seconds
muted.io - A magical collection of interactive music theory tools & visual reference pages for musicians and music producers
Sampulator - Make (and record) beats on your keyboard
Chordify - Chordify turns any music or song (YouTube, Deezer, SoundCloud, MP3) into chords.
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
Scale Heaven - Browse and play any scale/chord, chord progression.