SSO and OAuth

OAuth guides

http://stackoverflow.com/questions/3514579/can-anybody-explain-oauth-to-an-idiot – the second post has a good explanation

http://www.thebuzzmedia.com/designing-a-secure-rest-api-without-oauth-authentication/ – uses HMAC.  Good read about security and authentication.

http://www.cubrid.org/blog/dev-platform/dancing-with-oauth-understanding-how-authorization-works/ – understanding how authorization works

http://marktrapp.com/blog/2009/09/17/oauth-dummies/ – dummies guide to OAuth

SSO

http://www.sitepoint.com/single-sign-on-explained/ – SSO explained

http://merbist.com/2012/04/04/building-and-implementing-a-single-sign-on-solution/ – Building and implementing a single sign on solution