This is also how webrings operated in the 90s. I make a Diablo page, you make a Diablo page, we both have a common banner in the footer that references each oth

This is also how webrings operated in the 90s. I make a Diablo page, you make a Diablo page, we both have a common banner in the footer that references each other's sites and anybody else in the ring. (Don't forget to sign my guestbook!) They still do this with black hat SEO, since such sites aren't going to get any legitimate backlinks organically anyway.