Invention

Day One again I guess--I lost count.
This isn't really a 'day'; I just thought of a cool, useful invention whilst in the shower. In its infantile state, at least, my idea is this: A cell phone [or, probably cheaper and smarter, a walkie-talkie] that lives on the exterior of one's vehicle [bike, car, skateboard, but please nothing really trivial, except maybe a left shoe] and can be rung up by the vehicle's owner at convenient times, such as when the owner visits the City and neglects to pay careful attention to where she parks; this can be more or less troublesome, depending on the city and the length of one's legs. Therefore, this handy hood-mounted phone [or wheel-hub-mounted, I suppose] can be dialed by its lost pedestrian, and answered by anyone who happens to be passing by. Simply ask the person who answers the ring where said person/car is [approximate street address, cross-streets, colour of local awnings], and you've found your car again! Also could be handy in case of burglars.