Develop a crawler to find websites which support single sign on

I need someone to write me a PHP or python program to do following: It crawls the web to find all websites which support single sign on such as Login with Facebook. The crawler will extract following information from each website: website URL, login URL, a list of single sign on services supported (e.g., Facebook, Google, LinkedIn, etc.). As an example, freelancer.com supports Login with Facebook. The information you will extract is: freelancer.com, http://www.freelancer.com/#login, Facebook