What is OpenID?

The Short Answer OpenID is a light-weight, decentralized authentication mechanism that allows you to have one login that you can use anywhere on the Internet. To sign up for an OpenID, please visit any of the following identity providers: MyOpenID , VeriSign Personal Identity Provider, GetOpenID, MyLID, Sxipper

Echoes of Passport here, but with (hopefully) a greater chance of success. Anything that can be trusted and reduces the ridiculous number of usernames and passwords, is worth a go.