Auxy Music Studio - Auxy brings real music creation to iPhone in a simple and inspiring format.
zMors Modular - Full featured modular synthesizer for iOS
cassini - Polyphonic Synthesizer for iPhone/iPod touch
Slayer Espresso Machines - Beautiful American crafted espresso machines
nlog Synth - Professional Virtual Analogue Synthesizer ::: check nlogmusic at YouTube :::
Surge XT - Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.