Simon Jones has pot together a new post for the Zend Framework users out there wanting to add sub-modules to their application.
I quite frequently find myself wanting some form of sub-modules, usually in admin systems where one "admin" module just doesn't cut it for larger sites. Without modules we're stuck with an AdminController.php which obviously gets very messy, very quickly. With modules, we can have an "admin" module with as many controllers as we wish. This is fine, until a site needs to manage lots of discrete elements.
His solution was a bit of a "hijack" of the boostrap resource for the "admin" requests that would allow him to dynamically add modules thanks to some simple mapping. You can download his example here.