The IIS 7.0 architecture is designed to be extensible from top to bottom, allowing you to replace any part of the built-in feature set with a custom implementation that suits your needs. As a result, IIS 7.0 implements all of its own features on top of the public extensibility model. This design is found throughout the platform, from the modular Web server engine itself to the configuration system to the IIS Manager console.
In the Launch issue of MSDN Magazine, Mike Volodarsky demonstrates the IIS 7.0 extensibility model by creating a Response Modification Web server module that enables responses from IIS applications to be modified on the fly using configurable response modification rules.
The project includes a custom Web server module, as well as deployment and management features for the module via a custom configuration section and a custom management page for IIS Manager.