I've been interested in the Phidget Circular touch for a while now. My only problem is that I'm not a programmer so I could probably get one and then not be able to get it to do anything.
The device is a touch sensor in the shape of a circle. It can mount behind up to 1/4" of glass so it will be safe when in the car. I initially wanted it to work like an iPod interface and allow volume up/down, and ff/rw when circling. I also wanted to be able to single or double tap on specific locations to play, skip forward/backward, and pause/stop. Not knowing how to program this quickly forced me to move on to other idease until I found this:
Palm Music Player
It's a program to make your pda work like an iPod. Now, if they did it I'm sure some of you good programmers out there could write something to make the circular touch work. Take a look Circular Touch Site
So, how hard would it be to write a program like this to use as an interface in a car?