Submitted by infojunkie on Tue, 2006-09-05 15:30.
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.