1. Getting started with the facebook sdk for php,
https://developers.facebook.com/docs/php/gettingstarted/
2. JanRain Engage,
http://janrain.com/products/engage/
3. JavaScript Cryptography Toolkit,
http://ats.oka.nu/titaniumcore/js/crypto/readme.txt
4. LocalConnection,
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/LocalConnection.html
5. OpenID,
http://openid.net/