The Rails plugin Goldberg is really quite good for kick-starting a site with its permissions system and basic CMS. There is one small bug in it though, it doesn't like adding nested controllers in the admin console. There is, however, a simple work-around: simply go to e.g.:
That will load up the New Controller page which lets you type in a controller name and set the default permissions for it, so all you have to do is type in the name of your new controller, e.g.
, and it'll work just fine from there!
UPDATE: FYI this has been fixed in the latest v0.2.1.