The Twitter MoPub Android SDK, now supported by Twitter as a part of the Fabric developer suite, helps developers integrate advertising solutions into their Android mobile apps. The SDK can be used to add banners, interstitial, and native ads to an application. The SDK also offers conversion tracking and additional services to aid in embedding mobile advertisements.
Check-in app Gowalla puts a fun twist on location sharing by helping its users discover wonderfully-designed virtual items that can be found, swapped, and dropped all over the place. Developer Ben Dodson used the Gowalla API to put together Wallabee Travel Edition.