To understand what Foursquare–the app that rewards you for “checking in” at shops, airport terminals, and basically everywhere–wants to do for businesses, Tristan Walker, its business-development director, suggests thinking about stereotypical big-screen chefs: “You know how the chef in the movies always goes out and thanks the wealthy guy? We want to replicate that with software. The loyal guy doesn’t always look like the wealthy guy.” Foursquare also offers retailers many ways to customize rewards.