While I'd like to say it was something noble or a bit more interesting, I found it by searching on google for "gmail invitation." Your website was buried on page 39 I believe but I clicked on a lot of the links. I know it sounds like "he's only interested in gmail" and while I'm tempted to say "I'm an avid fan of your blog and just saw the post!" I'll be honest and just say I found it while scouring google for gmail invitations.In order to get more information, I've since signed up for a free web stats account with statcounter.com. Now I know that Cognitive Overflow has been found via searches for "lord's prayer in l33t speak slashdot", "kyte database independence", "i need a lot of money how", and, of course, many for "gmail", "gmail invitation" and the like.
Finally, check out this article at wired.com to read about VisitorVille, a service which displays traffic information in a SimCity-like way. Pages are portrayed as buildings, with the more popular pages being larger buildings. Visitors are shown as people and those who are referred by Google are shown arriving via the Google bus.