Internet Access CAPTCHAs
http://www.defectiveyeti.com/iacaptchas
"I'd also like to see certain people on the Internet prevented from doing certain things. You know, like: logging onto the Internet."
RSS CAPTCHA Prototype
http://kentbrewster.com/rss-captcha-prototype
"It's a prototype for mashing up publicly-available RSS feeds and using them as a sort of CAPTCHA."
TPCSv8 - Articles - The Cutest Human-Test: KittenAuth - Articles - The Cutest Human-Test: KittenAuth
http://www.thepcspy.com/articles/security/the_cutest_humantest_kittenauth
"Click 3 pictures of kittens to submit"