Hey, I just had an idea of how to build a flexible, stack-based navigation controller (à la UINavigationController) with a minimal amount of code. This is not so much of a production example, but rather a dev experiment I hacked up last night. Though there's the NestedList component, I was somehow missing a similar container for generic Panels.
The approach makes use of 2 specialized routes: map.connect('navigation/push/:_controller/:_action', ...) and map.connect('navigation/pop/', ...)
and a new type of controller, the 'navigation' controller, that maintains a history of 'pushes' and is able to rewind these. The controller only has 2 actions: push and pop. It enables you to write simple '<a href="#navigation/push/details-controller/index">Details view</a>' links as well as for example 'Ext.redirect("navigation/pop")' statements (i.e. useful for back buttons) and determine whether the new active item is pushed on top (do a slide animation right-to-left) or pop'ped from it (slide the view out left-to-right).