The user identification and privacy are among the hot issues of the Social Web. The Web ID , a new form of open ID using the Linked Data could provide a solution for difficult and complicated problems like remembering login details, passwords, and sharing private information across the many websites and social groups. 

The WebID outlines a simple universal identification mechanism that is distributed,
openly extensible, improves privacy, security and control over how one can
identify themselves and control access to their information on the Web.

The WebID Protocol embraces and extends OpenID. Furthermore, Linked Data
provides critical infrastructure for the WebID Protocol that enables an
innovative tweak of SSL/TLS.

Have a look my WebID
(http://id.myopenlink.net/dataspace/person/Bratsas#this)