SocialAuth
Java Library for authentication with social sites like Facebook
SocialAuth is a Java library (.NET port & Android version available) for you if your web application requires:
Authenticating users through external oAuth providers like Gmail, Hotmail, Yahoo, Twitter, Facebook, LinkedIn, Foursquare, MySpace, Salesforce, Yammer, Google Plus, Instagram.
Easy user registration. All you need to do is create a page where users can click on buttons for the above providers or other supported providers. Just call SocialAuth and you can get all their profile details.
Importing contacts from networking sites.