TC-11 for iPad
TC-11 is a trippy, fully programmable, multitouch synthesizer app for iPad. Rather than fiddling with a bunch of knobs, you interact with the app by tapping and dragging your fingers around the screen.
The sounds produced by the synthesizer depend on where you touch the screen and how your fingers move in relation to one another. Even the accelerometer, gyroscope and compass can be assigned to synthesis parameters so that moving the iPad around will modify the sound. Combined, these inputs and graphics make the app feel alive.
There are 112 sound presets built into the app, with the ability to build an unlimited number of your own. What you should do is watch this video to see TC-11 in action, then head over to the iOS App Store and pick it up for $30. It’s not a cheap app, but it’s so well-designed and fun that I think it’s worth the cost.