This vaguely reminds me of that (was it Internet Explorer?) plugin/extension that tried to detect phishing sites by prefetching all the links on a page. There was a big uproar with admins and there was an apache rewrite rule floating around to detect the user-agent and block these requests.

I can't remember the name of this, though, so I'm having trouble searching for it. Maybe 2006 or 2007 was the time?