Working on a number of public-facing sites, both for government and private sector, the issue of providing a SPAM-resistant contact form arises regularly.
The typical example which I have a serious personal dislike for (due to the fact that it takes several goes and a lot of luck) is Google’s reCAPTCHA.. some amusing problems with this and other systems are well documented at http://captchafail.tumblr.com/.
When researching the Audio version of Google’s CAPTCHA, I was staggered to discover how incomprehensible this was…
Sounds like the soundtrack to Paranormal Activity..
I’m in favour of logic questions personally… e.g. http://textcaptcha.com/
I will update with other options as we test/discover them, comments welcome!