The Asirra project is a Captcha alternative that shows you pictures of kittens and puppies to fend off bots and prove that the end user is a human.
Is anyone using Asirra (or something similar) in production? What alternatives are you aware of?
Is this technique common in the Captcha world? Is there a way to control the logic at the server side?
What are your thoughts on its implementation, alternatives, and how a more secure version could be made?