BlockXXX is a great extension if you are looking to protect your kids from browsing accidentally adult websites. Even in its very early stages, the extension provide the basic automated blocking features, but still not that powerful as you may expect. BlockXXX scans the actual HTML document for tell-tale words and phrases. If it finds these words it disables all images and hyper links on the page. This design in some cases causes pictures or links to be available for a couple seconds before they are disabled. This is obviously undesirable, however the option to move to a blacklist system is even more undesirable. Unfortunately too that the extension is not yet enabled for Firefox 2.0, but I find it a really great initiative that deserve to be encouraged.