Two of them at once, in Tonight's links and If only people would quote their sources. I've munged the links so they no longer point to the URL the guy originally mentioned, but if you're at all curious you should be able to unmung them manually.
Why do people do this? Because they think that they can game Google's PageRank system by forcing a number of (apparently) high-traffic sites to link to their own site. See Dive into Mark on comment spam for a comprehensive rundown.
