Here's two more: karmaplatform.com and kdcalc.com. This whole area of converting end user produced Excel solutions to scalable systems does seem very promising. But no one has nailed it yet, and I suspect there are at least two reasons. 1) Over technical solutions that require a .xls to be converted into some other technical deployable eg kdcalc.com producing a .jar 2) The diversity of Excel based solutions eg spreadsheet as DB vs. spreadsheet as calc engine vs spreadsheet as reporting dashboard.

So when you say "convert a spreadsheet into a web app", it means many things to many people. Which is a real expectation management challenge!