OpenID

OpenID  http://openid.net/get-an-openid/what-is-openid/

Gain Greater Control Over Your Online Identity

"OpenID is a decentralized standard, meaning it is not controlled by any one website or service provider. You control how much personal information you choose to share with websites that accept OpenIDs, and multiple OpenIDs can be used for different websites or purposes. If your email (Google, Yahoo, AOL), photo stream (Flickr) or blog (Blogger, WordPress, LiveJournal) serves as your primary online presence, OpenID allows you to use that portable identity across the web."