In the end, though, what percentage of webmasters/admins/whatever even check logs and stuff? There's gotta be many many thousands of sites that are wide open.
So if they have trouble breakling into your site, they'll just hack into Joe Blow's site and get pretty much the same stuff anyways.
pr0 - you seem like an enterprising guy with some good connections. You should be able to work out how to prevent the vast majority of the hacks. Maybe you should set up a business based on it
Could you make money on it if you charged webmasters per prevented attack rather than a set monthly? Or maybe a combination?