The Magic Piano by Smule
The Magic Piano is a fun tool basically offering a playable piano, while it offers a game mode I was just using it for improvisation. The different interfaces naturally facilitate different performance methods. The spiral keyboard makes playing octaves much easier though the rotating background robbed me of a possibly useful visual reference point. The circular interfaces makes playing continuous glissandos very easy.
Sylo Synthesiser By Matthew Rosenfeld
For such a simple synth there is a massive potential in sounds and then I worked I could sample sounds and use them as the foundation of the synthesis. In the performance setting the 100% feedback on the delay provides the opportunity to build a rich texture which worked very well as a foundation to under pin the ongoing improvisation.
I think there will be more iPad based performance to come and inevitably I have started looking at the SDK.