This document discusses location-based apps like Foursquare and how libraries can use them. It highlights how these apps work by checking users into locations and earning points. The document provides details on how Foursquare allows users to become "mayors" of locations they visit most and leave tips. It suggests libraries offer incentives for users to check-in and share their location. Finally, it questions how libraries can use these apps to improve access to information, market services, engage with patrons, and enhance learning while respecting users' privacy.