I’ve installed reCAPTCHA Drupal module as a way of combating the large amount of comment spam that I get on this blog, and to support the reCAPTCHA project. What a fantastic idea! I see that there’s already a term for using human expertise in a fun or transparent way to solve problems that can’t be solved by computers: bionic software.
ReCAPTCHAs are fun and add to human knowledge, but if you want to avoid them (they do take a little time to load) then create yourself a login. On the other hand, if you have some spare cycles, then you can do reCAPTCHAs on the reCAPTCHA site without creating lots of comments here.