Use your Palm PDA to control Winamp based Frontend(or use it as a lcd status display)
Okay I was playing around with my pda today and found this program palmOrb(http://palmorb.sourceforge.net/).
This program emulates a lcd status display. it could be used as a display on your carputer if you want to see computer stuff while your frontend is running. but what is really cool is that there is a release that allows you to control winamp with the program(play,pause,stop,repeat,ff,rr)
so basically its like a lcd remote for you carputer(either serial,usb,bt,ir).
it took me a day to figure it out so if you have any trouble setting it up I can try and help you out.