Rob Allen has made a new post today showing off Action Helpers in the Zend Framework.
When you have some functionality that needs to be shared across multiple controllers, one method is to use action helpers. Action helpers are very powerful and contain hooks to automatically run when you need them too, but you can ignore all that if you don't need it.
He includes how to set up the "helper broker" pointing it at your helper files and a simple helper that multiplies the input times two. This helper is then applied inside of his example action (in an IndexController, of course) and assigned to an output variable in the view. He's included a code download as an example.