foursquare-api-java is a library for implementing the Foursquare API in Java code. This is the updated version of an earlier Google code project by the same name.
The Votizen API aims to get friends to involve their friends in supporting candidates. The API website notes that the API is entirely based on HTTP. Votizen is based on the premise that, "Voters are more likely to listen to friends than campaign volunteers." Votizen is the first "social campaigning platform built entirely on personal connections."
App.net, a subscription-based social feed and API, has announced the release of the App.net Messaging API which allows developers to add messaging functionality to third-party apps.
