You have probably seen Fling, the joystick put together by Ten One Design that sticks right onto your iPad. And now the company has introduced a new version called the Fling mini, available for preorder right now. As you can imagine, the Fling mini is smaller than the iPad version, but Ten1 says it still feels like an analog stick and works just fine on the iPhone's haptic touchscreen.
I was very impressed with the Fling joystick when I tried it at Macworld earlier this year, and while it's tough to see how Ten One could replicate that same balance and feel in a smaller model, I have no doubt the company was able to do it