Skinput from Microsoft

If you haven't already heard, the brains at Microsoft together with researchers from Carnegie Mellon came together last week to debut their innovative solution to our touchscreen-centric world, a technological leap that transforms one skin into their personal touchscreen. Using a pico projector to beam graphics---namely, the keyboard and touchscreen menu---onto a user's palm and forearm; the device then uses the distinct sounds that are emitted with one taps the different parts of our skin to identify which icon has been tapped. In total, Skinput has five piezoelectric cantilevers to detect sound frequencies which can detect the different buttons, detecting the five skin locations within 95.5% accuracy.

Though this is at very early development stages, I expect we'll see more and more innovations like this in touchscreen technologies in the coming years.