Having just used instacalc i have to say it rocks! I couldnt be bothered to pull up the calc so i thought i'd try it. It definately is the best of breed between excel and the calculator - i can see why it got funded.

Plenty of potential where people have to share calculations/revenue models etc. Can see plenty of use in the financial industries and also in startups.

It's naive to think people will be sharing their financial models over the internet. While cool to play with, I really don't see a business case for Instacalc. Please fill me in on what I'm missing.

Well its simple - make them password protected.