Markus recently posted about extending the core of the Zend Frameworks MVC offering, Zend_Controller_Action.

Today, ladies and gentlemen, I'd like to talk about beefing up the most central component of the Zend_Frameworks MVC package: Zend_Action_Controller.

Markus does a great job explaining what he did and this should give you a good look into how to extend the Zend_Action_Controller for your own nefarious purposes.