Compromised IDs

I found a page with a number of compromised IDs for various pay sites (most of which appear valid). I know that's not uncommon on the web, but I was trying to think of whether or not to post the link here so that web masters could disable the compromised logins - obviously there are trade offs with doing so. And then it hit me, is there a business here? Imagine a web crawler that found these pages and then automatically categorized them by site. Imagine if an interface could be developed to automatically suspent these IDs without human intervention. Surely eliminating significant amounts of stolen traffic would represent some value. Am I nuts here? Is anyone doing anything like that yet? Is it a viable business?