David Burt, has wonderful resource for those interested on Web Filtering, that covers a number of resources (filters, law, policies, Internet safety and more), and features a very readable blog. The site is named Filtering Facts. I specially love his posts on Internet Safety, covering children protection.
This is a very comprehensive resource (hey, much to read for a quick visit), and David is very open to suggestions.
And also, David, many thanks for your cite!