SynthStation. Its creator, Erik, is also toying with some new code that'll let you use other iOS accessories to control various variables. For example, the Sphero. Sadly, we don't have a ton of details on how it works -- the developer is merely taunting us for the moment. But we can see that by lifting and tilting the interactive ball he is able to manipulate frequency and other parameters. Check out the video after the break to see it in action.