I should mention that I've never owned a GPS device. I don't do much driving and I'm too cheap to get any phone other than what's offered free with my telephone plan. However I recently took a trip to Portland with NJ and a friend who did have a GPS on her smartphone and we got oddly excited over the process of "keep the blue dot going along the purple line!"
So it occurred to me, why not make that a game? Have a GPS system that scores you based on not only how far or how often you drive but how well you drive? You earn points every time you don't miss a turn (complete with little fanfare noises). You could even have bonus points every time you visit a place you haven't been to before or points for going farther from your "home" base. The game could even have achievements that you could unlock for different destinations or creating unusual shapes on the GPS map (say doing a figure 8 through several blocks).
Bizarre little idea I had but I'm sure it'll exist someday.