Foursquare may be getting all the attention, but Gowalla — its scrappy Austin competitor — is more fun. Like Foursquare, Gowalla lets you "check in" to real-world places using your smart phone, and the site plots your location on a map for friends to discover. But where Gowalla shines is in the experience. The brightly colored badges and the zany-fun interface (as well as the ability to add photos and create trips around locations) make Gowalla the coolest interactive passport there is. (See Gowalla's mobile app.)