Google Social Graph
From Google Labs, those fine folks that brought you everything from Street View to every other application of any merit in the universe (only slight exaggeration) comes Social Graph.
Tired of entering all your personal data into Facebook, MySpace, Twitter, Friendfeed, Socialpia, or Volksden? OK, I made those last two up, but it can be tiring to try and capitalize on the great social networks out there again and again, hoping beyond hope that they don’t fade away into the social ether. Social Graph can help.
“With so many websites to join, users must decide where to invest significant time in adding their same connections over and over. For developers, this means it is difficult to build successful web applications that hinge upon a critical mass of users for content and interaction. With the Social Graph API, developers can now utilize public connections their users have already created in other web services. It makes information about public connections between people easily available and useful.”
So you can put a social application on your site that allows those who join to capitalize on their existing social networks. Neato.