Animoog | Moog Music Inc
I'm not sure how much you guys are into the funky synth stuff, but for .99 cents, this is a lot of fun. I think it's compatible with a hardware MIDI keyboard too, if you use something like the iRig MIDI or Midi Mobilizer II.
It's also got a virtual keyboard that's really well designed for the interface.
Looks pretty cool. I'll have to check it out.