But why would you bother charging for it, when you are likely to be able to monetize it well if you got any traction.
The question if you would pay for it is directly because of Jason Cohen's post. If it's not worth paying for at some level, it's probably not a problem that's really screaming for a solution.
I'd pay for Google, for example. The fact that I don't have to pay for it is nice, but I'd cough up every month for it if it was a premium service, because it does something I absolutely need.