New login to my website

I want to make a new login to one of my websites.
http://quizstone.com/en/ 

The idea is to make it as simple as possible for the users. About six months ago I made a Facebook login, but this has not proven to be a perfect solution. People can still create an account, but I want to make a more generic solution.

The idea is to use OpenID
http://openid.net/developers/libraries/

I want to follow this tutorial
http://qpleple.com/how-to-make-people-login-into-your-website-with-their-google-account/

But make it use Google, Facebook, Yahoo...I will report to you when I'm done. Please let me know if you have some ideas, or tips...

Have a great day!