This, I think, is a new one.
I have received a piece of spam (sent via an insecure host in Ukraine) that appears to be an innocuous request by one blogger to exchange links with other blogs. The problem is that the sender is nobody I’ve ever heard of, and the blogs aren’t particularly on the same subject as stuff I write about (if anyone figures out what subject I’m writing about, please let me know).
The blogs in question appear to be legit blogspot-hosted blogs–and they have on-topic content–except that the sidebars are obvious link-farms, as is the website associated with the sender’s e-mail domain.
So what we have here is an attempt to get people to act as part of an unpaid link-farm. More polite than comment-spamming, I guess.