I am no longer with this company, but it was a small web dev company that had a problem with insecure legacy code on just about all 200 of its clients.

I wrote a software firewall to prevent the exploitation of these insecure websites as well as a monitoring system to identify any websites that got compromised in other ways.

It moved us from spending 80% of our time recovering endlessly defaced websites to 5%, pushed us on to newer and bigger projects, and made several hackers and at least one pen tester actively curse the systems in their exploit code.