Isn't this the second post lately on nice mini-tools which probably can't easily translate into a startup? There is a difference between just a web app and a business, right?
A start-up is a small business with a lot of growth potential.
It needs:
1) Revenue streams
2) Revenue streams
3) Revenue streams
If it's missing any of these three, it is not a business, and hence not a start-up.
PS: Sometimes the revenue streams are not active yet, but there needs to be a way to make money from it!