In a recent thread I had asked about a need I had to fulfill a clients request. The need was fairly simple: allow the admin user to manage a list of links that appeared on every Page.ss in the CMS.
At first I had considered creating a special page type called GlobalLinks.php as an extension of Page. Then I would remove all of the tabs and fields except one tab that had a DataObjectManager to allow for managing of these links (drag+drop sorting, editing, add/remove, searching etc). However this has all sorts of problems including: 1.) the Page.ss will have to control the specific page name, if this changes by the clients unawareness - it breaks. 2.) The admin will see the ability to create more page types called GlobalLinks and they are essentially useless.
So then, with some help from stuckinrealtime on the forums, I setup a ModelAdmin. Unfortunately this is only a data manager. It does not allow for extensibility for such things as DataObjectManager (which provide the convenience as mentioned above of drag+drop reordering and instant listview without having to click 'Search').
So that is where I am now. I see the need for an extension of ModelAdmin called ModelViewAdmin. This will allow for more view flexibility when creating a ModelAdmin type class. You could be able to apply tabs/textfields/viewmodules such as in the SiteContent. This is probably a tremendous amounts of work, as it is certainly beyond me at this time - but I thought I would share this in hopes of some feedback as well as a chance of being developed in the future.