Bung it in a drawer until you have a car that works with it. I have an iPod Classic with a 60GB hard drive that just stays in the car permanently plugged into the iPod connection. It still works perfectly at the moment, but even if the screen and battery don’t work, it could still perform this role perfectly, as it takes power from the car, and you choose tracks through the car stereo screen.
I don’t like the look of the current nano – seems to small to be usable to me. Some places might be doing good deals on clearance models of the previous one.