NanoStudio is a nice synth software, free for OSX and WINDOWS; there is a paid version for iOS.
I suggest to look at this video showing some features about the iOS version:
[sz-video url=”http://youtu.be/Stcf_8H_qVM” /]
It’s true, on touch-screen NanoStudio offers more flexibility, but I tried it on Lion – it runs very well – and after a little bit practice I could obtain good results.
On YouTube you can find more videos about it, in italian language too, meanwhile this is a playlist:
Here for the downloading page: www.blipinteractive.co.uk