SMK Corp. has a solution for all of us that like to draw and "cipher" in the air. Called the Wireless Input Pen, the device incorporates a triaxial accelerometer that can detect your airy gestures and translate them to input (letters, etc.) for a computer.
The pen is connected to a host computer via Bluetooth, and it has a reported range of 10 meters from the host. This allows for the mad gesturing to take place all over the room – you can virtually cover the walls when the mood hits. Now how cool is that?