Referrer spam: The end is ROI
The first two claim to be UNDER CONSTRUCTION, and this makes my hypothesise that they are honeypots of a sort, respectively researching whether Deep-URLs (“/friendslinks.php”) or merely Root-URLs (“/”) are most effective methods of Referrer-Spamming, plus also providing a check to see which blogs are the most valuable ones to be worth spamming.
In short: I hypothesise that the referrer-spammers are now doing ROI (“Return On Investment”) calculations.
writes Alec Muffett. Go read it.