A database with a spreadsheet front-end would be incredibly useful. We would like to try and build something like that.
But it's also a hard product to market because for every vertical use case, there are better targetted tools than a generic
spreadsheet-db app. See this Quora discussion for some more info on DabbleDB - http://www.quora.com/Why-did-Dabble-DB-never-get-any-tractio...
I think the ideal route might be to grow into that product instead of trying to build it from day one.
