The gist is that children should learn never to give out personal information over the Internet nor meet in person anyone they've met on the Internet - at least not unless it's in a public place, with an adult present. The site question is a bag of worms - but you sometimes can round up the worms. If you have an Online server like AOL, Erol's, etc. There's software that can be bought. And there are various services.
Most screeners use the sites' own ratings.
You can find this stuff and much more just by using links from one site to another. They should be using technology, not regulation, to enforce each parents' choices. Your kids also shouldn't be locked in their room with their computers. The computer should be located in a central family location. You should be computing with your children.