I run into lots of instances of my site linked to by people I've never heard of. When I go check them out, I see that what they have done is do a search on Google on a keyword, grab all the results, then put them on their page as "content".
I know you think that's nasty, Ian, but in fact that's just what a directory is all about. You mention a lazy way to create one, to be sure, but it's a directory nonetheless.
When I get stuff like that I look in the email headers and report the spammer directly to their ISP as well as whoever is hosting their web space. I figure if they sent it to me, they most likely sent it to 10,000 others too.
Randy, please think twice before reporting spam. As wrong as what these guys are doing in terms of search engine spamming, they are not email spamming. They made a legitimate contact with a webmaster for links, just as if I send a news release to multiple media contacts or a resume to many HR contacts with potential employers.
They deserve to have their website banned from the search engines, and I hope they do. They do not deserve to have their website shut down by their ISP (often forced to on a single unverified complaint received by MCI or ATT or whomever). This happened to me on a false accusation -- a heavy penalty (shutting down one's entire livelihood) on what amounts to gossip (a single unverified report).
On the Internet, there is no due process, so it behooves us to be very careful to make sure the punishment fits the crime. I did report all 263 sites to Google, but I won't report it to their ISP. As much as I hate spam, it is a minor annoyance compared to suddenly having no income.