What I think you should also consider is the MS Access angle. What made Access so popular in enterprises was that they could basically build a Windows app with almost no programming skills. Define your tables, build some forms, install the runtime for people–BAM. You're done.

In my opinion, that would be a necessary component to this idea. You need to have both spreadsheet-like data viewing and form-based data entry.

I suppose that's what Wufoo and Dabbledb already do to some degree, but I think there's more you can do.

If you combined: - spreadsheet-esque data viewing (maybe with some formulas) - form-based data entry - good sharing tools - permissions - import/export tools - some database templates that let you spin up stuff fast

Then targeted it at some big verticals, I think that would be a good start.