One of the most common and discouraging issues related to maintaining a blog or any other system permitting user-driven comments and moderation is the persistent annoyance of spam and related content. Unfortunately measures such as Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA’s) have become increasingly susceptible to being bypassed or relegated to a best-available security measure in the prevention of spam partially due to the increasing capability of technology and problem solving investment by hackers more commonly through the addition of a human workforce, often compensated, for solving various CAPTCHA puzzles. Another popular method is reusing the session ID of a known image or leveraging a client side image for translation and submission to the server. Recently while having some discussion on the topic, I found over in Microsoft Research they are working on a system known as Animal Species Image Recognition for Restricting Access or Asirra. Asirra differs from CAPTCHA’s being a human interactive proof (HIP) by asking people to identity images of cats and dogs (courtesy of PetFinder.com). The task of identification is particularly difficult for a computer, but is easily solved by people and supports a good cause. Asirra uses the PetFinder.com database, consisting of over 2 million images, adding to its overall security and complex challenge-response system. The best part about Asirra is it’s FREE! For more information on the Asirra project visit http://research.microsoft.com/sn/asirra/FAQ.aspx.