The most reliable source of such information appears to be referrer logs -- and the growing plague of referrer spam will soon make them useless, too.

It appears that the combination of mindless greed and technological ineptitude is steadily eroding the value from what was once the glory of the World Wide Web: mutual hyperlinking.

The only problem being, as you note, that referrer logs are basically useless. I even locked down my stats page so that it was not accessible other than locally, but I don't really look at the referrers there any more, because I cannot keep up with the effort needed to filter or block all the different domains that referrer spam can come from.

Actually referrer log spam is the one I don't get: the referrer log is not published anywhere (on virtually any sites), so referrer spam can't drive up page ranks on Google or other search engines. No one but the admin generally looks at referrer logs, so the spammer won't get any hits from them. What the heck do the spammers think they're getting?

I think the problem with referrer spam was made worse with the introduction of products like Expression Engine, which comes out-of-the-box with a referrer display template. While almost everyone has hidden or removed their referrer display page, the spammers have continued their onslaught in hopes of catching those few that are left.

Heck, it costs them next to nothing to hit the referrer logs and since when have spammers cared about the resources they use on someone else's system?

Oh, and there is at least one juicy referrer target still out there: Little Green Footballs. And, of course, Charles has been fighting the robot swarm to keep his referrer page clean. I wonder how long he'll keep up the battle...

My guess is that the Ecosystems problem is purging. Bear apparently doesn't either do full checking all of the time or purge off counts of old links on a timely basis.