Delegated Authentication through a Login Provider

Nowadays it is common to see many internet sites delegating the authentication process to some third-party providers such as Google, Facebook, Twitter, etc.

So essentially you do not have to register and create a new login/password for the site. You can just use your existing login credentials of google, facebook, twitter, OpenID, LiveID, etc. Behind the scenes, the application and the login provider use standards such as OAuth and OpenID to do the magic.

The advantages of delegating authentication to a popular third-party provider are:

1. Users don't have to register and create another set of username/password for your site. Thus the user has fewer passwords to remember.
2. The application does not have to worry about creating a Login form and SSL enabling it.

Found 2 good libraries on google-code for enabling OAuth delegated authentication on your application:
http://code.google.com/p/socialauth/

http://code.google.com/p/socialauth-net/