After some experimentation for other things I had the idea that the Treo 300 combined with an unlimited Vision plan from Sprint might be useful as a source of network for the empeg while in the car.

There are a few gotchas, though:
-it would need the serial port, or it would need to take over the IR port so you could run ppp on it. (or you'd need another computer)
-you'd need pppd running

But most importantly...
-what would you do with it?