I had a Microsoft Sidewinder Gamepad sitting around collecting dust, so I decided to try it out as a controller. I haven't tried it in the car yet, but it is working very well on my home pc. One down side is that it doesn't have the numbers to select a specific song. Another downside is that you have to run in Win9x with Explorer as the Shell. But it looks nice and works well.

Here's how I did it. Run winamp with the Carmp3 Plugin. Use Sidewinder Profiler to set up buttons. If you don't want to run Explorer you can try and use a joystick plugin, but most of those won't let you take advantage of all 9 buttons.

*note I'm currently looking at the possibilities of setting up a song selector for it*

GR1NCH