I got turned on to Phidgets recently.
Some interesting stuff here. One that looked really cool was the accelerometer. It’s a little board with a chip that can detect how it is tilted. It reports a value of -1 to +1 on each of two axes – left/right and back/forth.
It plugs in via the USB port. You run a little server that the phidgets connect to. There are AS2 classes (along with some other language stuff), which I converted to AS3. Then you just make an instance of PhidgetAccelerometer and listen to events on it, read values off it, etc.
I used it to control a 3D form.