If you've already found all the GPS caches (and the missing time capsules, while you're in there) and if you've already drawn all the GPS drawings you're going to, then hang out a little bit and wait for the advent of Geeplogs, "public GPS contexts that can be queried about a given area. [They] will be the GPS equivalents to blogs, in which a person could narrate a specific tour with his or her relevant commentary, possibly with photographs or video feeds."

When we were teenagers, if you gave a place history, they called it "tagging." They, whoever they were, were prescient.