iPod Map it’s not, but it’s close.
A free online service developed by Zap Technologies allows you to get driving directions and export them to your iPod. The result is both text and the map image itself, with the text being step-by-step, turn-by-turn directions. If you think it looks like Yahoo Maps, you’re right. That’s the inspiration.
The directions you download are in the form of a ZIP archive, you simply uncompress them to your iTunes photo folder, and view a sequence of GIF files on your precious. The iPod is not the only MP3 player you can use to take advantage of this service (any with GIF support will do), but it is certainly the one getting the most press.
The only restriction on this service seems to be that the to and from have to be in the U.S. or Canada. And if you go off course, you are SOL.