OAuth

 OAuth an open protocol to allow secure API authorization in a simple and standard method from desktop and web applications.

 Almost all Social networks  provide a method to share there data  with data with others by the method of OAuth. By this Authorization  for example if i am integrating Twitter with my website the user dosen't need to provide the uname/password of him in my site but they can authenticate in twitter itself and he can give allow permission so that he can view his Tweets and post of others and can Tweet from mysite to Twitter...
This is a  good technology as OpenID. very very Secure.

I have implemented it already for Picassa,Twitter,Facebook and Youtube. for example u can check this site in development stage.

http://208.109.209.105:1081/phaseoflife/