If you're not into videoconferencing but you're into gaming, researchers have come up with a clever alternative use for your smartphone's front-mounted camera. A rubberized accessory device mounted ahead of it, containing a patterned grid and able to let in sufficient light even with your finger on top of it, transforms the image sensor into a three-axis analog joystick. Not only is it more intuitive than a capacitive touch sensor-created virtual joystick alternative, it also frees up touchscreen (and more general display) real estate for other purposes. More coverage comes from:
And here's another descriptive video, from the 2004 SIGGRAPH (where the joystick was then labeled an "emerging technology"):
