@woozle @bstacey I haven't noticed anybody saying they've tried that specific approach, but it sounds worth a try to me. I've seen two related things though. One was somebody fighting the new botnet scrapers by modifying the outgoing links on every page to include the client's IP address, checked when requesting the target of the link, such that if you distribute links you find to crawlers on other computers, they can't load them. The other is PrivacyPass, a specification that's a few years old now, which gives a visitor tokens that can be issued by one server, verified by another, and can't be linked to each other, so people can browse anonymously but still reuse the result of a captcha or other verification multiple times.