I want to modify the django-admin app to see how far it can go :) I have found some interesting projects (django grappelli) mostly focused on skinning, more interesing django-admin apps out there?
Looking for students project :) ideas are welcome too :)
Its "Max"? Its only limit is what you can think of; it's just a website after all.
In terms of what might be useful, here are a few things I'd like to see (as somebody who builds commercial sites with Django):
A statistics/logging tool that shows reports in the admin
A framework for making reports for models display easier in the admin
Improving the whole admin navigation bar with global navigation links as well as something like grapelli's personal bookmarks.
Integrating a todo list (it's simple to do but could do with some focus on the front-end experience so the list persists between pageloads, etc) that you could generically link to models and instances (eg: "Create new page for 'about us'" that could link straight to the Flatpages admin or "Edit home page to show latest prices" could link straight to the Flatpage for the home page.) It could get complicated.
But those are things I would like. It would be much more enjoyable for you if you went with something that you found important.
It seems that GondolaCMS made a lot of changes, but it's not open-source. Ella CMS and django-cms made also good effort, and they are open-source.
This is also of great value http://www.slideshare.net/lincolnloop/customizing-the-django-admin