iPhone Keyboard Hack
Our buddies over at Perceptive Development have pulled off a stellar hack: they've hooked up an external keyboard to an iPhone using an audio modem implemented with a $20 micro-controller.
The result is a way of communicating with the phone using the Apple-approved SDK audio input, and in this case sending encoded keyboard inputs to it. So this hack can be done on a non-jailbroken phone... genius.
Nicely done fellas!