The Meta-CAPTCHA (Score 1)

Let's make an assumption that the internet will eventually solve any problem you throw at it given enough time...

What if rather than working on the next best CAPTCHA system, sites were to work from a rotating CAPTCHA repository?

Each page load presents a new human interface problem, something simple like a jigsaw puzzle or an image of a tic-tac-toe board with instructions to place an X and an O in a winning/defending position. In addition to each visual directive, there could also be a random text directive inserted to compound the problem (i.e, saying something like "after selecting the item, wait at least X seconds before clicking X button.)"

If your thinking in pseudo-code, the parsing of the text input isn't particularly challenging, and something like the tic-tac-toe is a solvable image problem, given time. However, if the captcha is being drawn from a growing database of imaging problems/verbal directives, then the captcha becomes not only solving the captcha, but identifying what kind of captcha is being presented.

As the captcha count increases a spammer/coder would have less and less time to hit the moving target and distribute their script before the next problem appears. This doesn't solve the problem of 3rd world captcha farming, but at least people might eat as a result of that economy.

This seems to me like a viable solution for the time being, though I'd like to refer to my first assumption for the long-haul.