MotionCAPTCHA, a jQuery plugin, based on the HTML5 Canvas Harmony procedural drawing tool offers a different type of captcha byasking the users to draw shape they see in the canvas in order to submit a form. It is not only different but also fun and can even be easier to-use for touch devices.
The project is currently a proof-of-concept considering the captcha is only verified on the client-side and can be manipulated. However, the next version is planned to have server-side and better browser support. Looking forward to it!