ICANN, the folks who decide how domain names work, have just approved the .xxx extension, which will allow porn sites to be more easily filtered from those who don't want to see them.
In theory, adult web sites will start using the .xxx extension, which you could then block from your browser (or search exclusively for, of course). It's a good idea, in theory, although there's no law saying a porn site will have to use it, so it'll be more of a volunteer thing. We'll see if it catches on. LINK