How about this one -
http://jessen.ch/articles/captcha
Well, of course it can be broken too - it's only a matter of money and
time, both of which are critical to spammers.
(for the moment it has a limited number of questions and only in
English).
Interesting. How well does this work? I'm interested because I wrote a number to text converter which could be used as a CAPTCHA and it was eventually broken, so I resorted to the more traditional image based CAPTCHA. For example:
Enter the following in numbers:
Four thousand and twenty two.
And of course the answer is 4022.
--
Richard Heyes
Employ me:
http://www.phpguru.org/cv