idcheck
apache cookie SSO mechanism.
Cookie based web authentication and single sign on system for largish intranets under a single domain where many, untrusted, people run their own web services. The server uses a private cookie scoped only for the client browser and the idcheck webserver which is always protected with SSL.
In addition to the common practise of using SSL for everything (which idcheck supports). The idcheck system can also be used to provide authentication to websites where you merely want to hide content from...