drupal

The idea is to create a new node type that refers to a node on another Drupal installation. The node content is always fetched from the remote site, although taxonomies are local. This will reduce the amount of duplicated content and enhance cross-site linking.

A node type that implements the Composite design pattern. Nodes of this type merely refer to a list of other nodes, and they are displayed by displaying the referred nodes in order of inclusion. Composite nodes would be useful to associate nodes of different types together to form a bigger logical unit.

I have seen it, it's called Dabble DB, by a small Vancouver software shop. Starting from an Excel sheet, you can create a full data model and associated CRUD operations incrementally. Watch the 7 minute demo, it's breathtaking.

Of course, Dabble DB is not without problems. The biggest in my opinion is that, being web-hosted, you cannot add new custom importers, exporters, views, etc., except through the company itself, which will find itself flooded with such requests. Also, I think that some data modeling cases will be found missing.