I've got a suggestion/feature request which I'll explain by providing an example:
An app named 'book' with the models 'books' and 'categories' and an app named 'magazine' with the models 'magazines' and 'categories'. When I use the admin interface and I add or change a category for 'book' then the only way to know you are in the 'book' app is by looking at the URL. The title of the page tells me 'Add category' and the navigation bar tells me 'Home > Categories', which is exactly the same for magazine categories. I think it would be more user friendly if you can see (by just looking at the page) in which app you are. Maybe a title like 'Add category (books)' or 'Add book category' and the navigation bar with 'Home > Categories (book)' or 'Home > Book categories'.
The navigation bar could even show 'Home > Book > Categories', that introduces a new admin view which shows all models for one app.
By the way I'm using the trunk version. I'm new to Django so I can't provide you with a patch to add my suggestion (yet!).