I saw this referrer list on another website
(designflea). When a visitor follows a link to you page, a script notes where they came from and adds that address to the list you in turn see on the page.
I thought this was a cool idea just because it makes the page seem smart and it's a nice way of saying "thank you" to the people who link to your site.
But I was thinking about it recently, and I realized that it's much more than this. If a group of pages all have a list of referers on them, and the links in the list are weighted by the frequency with which they are used, then pages that surfers jumped back and forth between will show up higher on each other's lists.
Once a link bridge gets added between two pages, it should eventually get voted up or down in the list of referring links depending on how relevant it is. So it may be that a web comes into being, created by the people who surf the various web site.
Update:
7/11/02: saw this article about the same thing:
backlinks at o'reilley
and again (claiming to have invented the whole idea)
at disenchanted
Dated: 06/17/2002