When the popular location-based social network Foursquare launched, it quickly attracted users with its game-like features. Now, with over 170,00 users, the service has rapidly become a huge source of data about the popularity of businesses and locations. In November, Foursquare gave developers access to some of this data by releasing an API (check out our Foursquare coverage here). Several applications that used the API were available at launch, with many more on the way. From shopping to games, here are four applications that really show off the potential of Foursquare's API.
