Cute project from Microsoft Research (who knew?): Asirra

Asirra (Animal Species Image Recognition for Restricting Access) refines captchas by asking users to identify photographs of cats and dogs and is offered as a free web service.

They’ve partnered up with petfinder, who provided Asirra

with over two million images of cats and dogs, manually classified by people at thousands of animal shelters across the United States. In exchange, we provide a small “Adopt Me!” link beneath each photo, supporting Petfinder’s primary mission of finding homes for homeless animals.