Infrared LED pointer
This is a little project we put together back in 2011. It's an infrared LED pointer designed to be worn on your index finger. The on/off switch is operated by your thumb. It's designed to be light enough that you can leave it on while typing.
We used a Wii Remote along with the free and handy DarwiinRemote software to capture the location of the Infrared LED. This allows us to use the pointer like a computer mouse, moving the cursor around the screen just by pointing.
The circuit itself is quite simple, the LED is attached to a small watch battery via a switch. We used Plastimake to encapsulate the battery - Plastimake is a good electrical insulator. We also made a Plastimake ring and a small backing pad for the switch to sit on to make it more comfortable.
Although this gadget was really fun to play with, we ran into the same problem that almost all vertical touchscreen systems encounter: Gorilla Arm Syndrome. Holding up your arm and pointing at a screen gets quite tiring quite quickly. On the bright side, using this gadget feels like you've stepped into the cyborg future, if only for a few minutes!