The internet filtering business is a lucrative one. In October, US company Websense reported third-quarter earnings of over US$90 million, putting the company on track to exceed its previous year’s revenue of a third of a billion dollars. There's a lot of money to be made in providing personal filter software to concerned parents, schools, companies and libraries, and even more from selling ISP-level filtering systems and constantly-updated lists they're based on.

And, of course, there's a lot of money to be made from selling them to governments, particularly governments keen to ensure their populations don't see problematic content.