The ATK Framework is a PHP business framework. It is targeted at developers who wish to focus on business logic instead of coding HTML. ATK provides a complete framework that requires only small amounts of code to get usable applications, while maintaining full flexibility. ATK has a model driven approach, but is 100% customizable.
Address Book Continued is a multi-user address book Web application. It also makes use of AJAX, which means that page reloads only happen on login/logout; the rest of the operations is handled asynchronously in the background. It's well usable, even over slow connections. You can even install ABC on your desktop PC and configure it so that it doesn't require login for connections coming from the local computer.