Comment Javascript will kill this idea. (Score 1) 168
Everyone has been focusing on the how easy/difficult it would be to reverse this hypothetical algorithm that would determine based on your use of a webpage if you're human or not...
1) server side. The only variable you could track is time between page requests. Don't see how that could possibly be enough information
2) Client side JS. Simple, just modify the JS to return &isHuman=true
3) Client side JS acting as a keylogger, sending back for server side verification. Harder to defeat, but you'll lose my business, the business of all of my friends, and have a horde of angry nerds picket your offices.
Also, this doesn't take into account any edge cases, for example if I've already been to your site, surf straight to