Why aren't you charging money? Excuse me for being blunt, but this is seriously silly - your purpose is to find if anyone will pay, right?
Also, one feature I myself would pay money for is sha256 validation of the content of specified files (html, js etc). Since I'm using AJAX I don't really have a problem with dynamic content. I want to be notified when/if my site is defaced. I will pay $5/month and consider it a real bargain, if you have multiple monitoring locations to make it hard for defacers to serve selective content.