One of the interesting aspects of Foursquare, to me at least, was that I would achieve points and badges for different check-in's to businesses. One point for checking in, a couple more if I'm the mayor of the location, and still more points for things like being the first of my friends, or checking in to five of the same kind of business within a week. These points aren't worth anything, of course, but they would accrue over the course of the week and Foursquare will actually tell you how you rank according to the other people you're connected with.
