I say we're going about this whole thing bass-ackwards. In most communities, zoning laws prohibit adult entertainment close to schools. The Web needs a similar approach. We let government define adult content and penalties for those who don't abide. Parents, teachers or librarians simply set up a filter to block .adu sites.
Web sites can publish whatever content they want, as long as they use the .adu label.
And would get past good intentions and go straight to results. Use the TalkBack button to tell me what you think. Or jump to my Berst Alerts forum to talk it over with other readers. And please take today's Quick Poll. Although I agree with your idea, it'll never work in practice for the same reason you say filtering software won't work.