Call this one Foursquare's wacky little brother. Gowalla makes the most of the game part of location-based services in this app. It's colorful and plays well with Facebook and Twitter. However, there are a number of bugs in the Android version, the most prominent of which is in the ability to drop and pick up items (part of the game). It doesn't always work, and that's a common gripe on the Gowalla forums. Still, it's fun to play with and is a nice alternative to the more minimalistic Foursquare.