Tim Bray explains some of the weird referer spam we've all been seeing:

Near as I can tell, pretty well every somewhat-visible website in the world is seeing its logfiles fill up with with bogus page fetches there only as a vehicle for a spammish "referrer" field; whether or not the site posts referrer data. This high-volume flood is a fairly recent phenomenon, and what makes it weird is that the vast majority of the bogus referrer sites are off the air due to some terms-of-service violation. It would appear that a sleazebag somewhere launched a really ambitious assault on the whole world -- using, I can only assume, a few zillion zombified drone machines -- only to be found out and have their hosting yanked while their mindless slaves continue to spew vacuous venom into logfiles everywhere. Damn, the Internet is a weird place.