K9 Web Protection
K9 Web Protection - Free Internet Filtering and Parental Controls Software
The thing that finally tipped me off to it was I started in safe mode with networking and when I opened up IE, it gave a custom error page that said the K9 filter wasn't working properly. So I'm not sure how it works but it works without changing any of the usual network settings. I had to completely uninstall it before it would let me do anything.