ReSlice - Slice your audio with an advanced, rhythmic arpeggiator and FX.
Skip Tunes - Control iTunes, Spotify, or Rdio from your Mac's menubar
cassini - Polyphonic Synthesizer for iPhone/iPod touch
Baritone - Spotify controls that live in your menubar.
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
Soundiiz - Transferring playlists between various music streaming platforms.