ReSlice - Slice your audio with an advanced, rhythmic arpeggiator and FX.
mixmello - mixmello is a free, open source tool to create remixed versions of your favourite playlists.
cassini - Polyphonic Synthesizer for iPhone/iPod touch
Incredibox - Express your musicality, pump it up and chill
nlog Synth - Professional Virtual Analogue Synthesizer ::: check nlogmusic at YouTube :::
Musicroamer - A visual Pandora for discovering new music