Pointing links at popular websites to attract Blogger Web Comments extension users brought moderate returns. Actually, just one link. For some reason, the only link where my post showed up through the new Firefox extension was the (personalized) Google homepage. I linked to a ton of other sites in that post, some of which I also mentioned by name, but only the first went into effect. Google seems to have put in safeguards to prevent just the kind of abuse I was attempting.
My post was the most recent listed for the Google homepage for about 8 hours (in the middle of the US night) and produced about 40 unique hits. Not overwhelming, but not insignificant. (I think I got about 25 cents in ad revenue, so it’s definitely something that could be exploited for evil). If all the links had worked, it would have been many times that. I may try a more controlled test, with short separate posts linking to popular (but probably not too blogged about) pages. Of course, the results were high partly because lots of people were testing out a new product and saw a blurb mentioning that very product, so the game would get old fast if spammers tried to take advantage of it.
However, other sites are reporting that just such abuse is occurring already, with a wide variety of spam. Fortunately, the most interesting and unknown a site, the more likely you are to check out the comments and the less likely it is to be spam-linked. But it still dilutes the value of the extension.