ReSlice - Slice your audio with an advanced, rhythmic arpeggiator and FX.
Spotify - Map shows when two people play same song at same time
Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
Playlist Machinery - Tools that help you create & organize your Spotify playlists
cassini - Polyphonic Synthesizer for iPhone/iPod touch
Magic Playlist - Get the playlist of your dreams based on a song