Can everyone just stop a second from the semi-masturbatory tech-talk about the ultimate CAPTCHA that no bot will get around and that all humans will be able to recognize, without using any browser never than 1992. Please :P
We can all agree that the VAST majority of users will be able to view an image CAPTCHA, and solve it. Like, 99.5% atleast. So the question is, what do we do with the 0.5%? I want to reiterate my earlier point, why not just provide an email address, either to something like OTRS or the helpdesk, or to a special email solely dedicated for this purpose, where people will be able to set up an account for them?
Doesn't this sound alot more sensible than wasting developer time developing an ultimate text-string that will, at best, make us look silly. Also, it would take up huge amounts of contributor time just figuring out the "questions" or whatever.
"If you have problem seeing this image, or signing up in general, please contact someone@wikimedia.org with your account information, and we will assist you in creating an account"
That's all it takes. That's IT!
--Oskar
PS. Sorry if I sounded slightly rantish, but jeez, the suggestions you people have......