Some stuff, to protect ur stuff.
ModSecurity for Apache 2.0 is now available. The exciting new features include XML support, event correlation, transaction scoring, anomaly detection, data persistence, a wealth of anti-evasion functions, regex back-references, support for sessions, and many more. This release further increases the flexibility of the core engine and enables you to do what you want exactly when you want it.
Oldy but Goody
phpSecureSite is a modular authentication and session-handling system for PHP, released under the GNU GPL license. It is primarily intended for use in closed web-applications, where users are required to enter a username and password to gain access. It is made to be fully integrated with the web-application, so that users will not notice that you are using a separate authentication and session system. This means that you must code the front-end (such as login screens) yourself. More information can be found on the about page.