The LinkOpenID extension allows a user to use his user page as a OpenID identifier by delegating authentication requests to an external OpenID provider (see openid wiki for an explanation). The extensions adds a new tab to user preferences on which the user can specify his OpenID and the URL of the OpenID server authentication entry point. The values entered will then be put into <link>-Tags in the header of the user page.
see also Extension:OpenID which allows this, too, and is working with MediaWiki trunk version. --Wikinaut 20:10, 10 February 2012 (UTC)