Ok, for the urbanites we need a little different game. Here's how it goes...
GeoCacher finds an urban location that has a unique name or number at the published coordinates. The name or number could also be written or stamped at the location. The location could also be a favorite restaurant or bar the stasher wants you to visit.
When the hunter visits the site they learn the name or number and emails it back to the stasher.
When the stasher verifies the finder 'got it right' they send a favorite picture, sound file, or software from their hard disk to the finder.
For thanks, the finder can then send some favorite data back to the stasher, these favorites could then be traded from disk to disk.