title: Is there an Unobtrusive Captcha for web forms?
body: <p>What is the best unobtrusive CAPTCHA for web forms? One that does not involve a UI, rather a non-UI Turing test. I have seen a simple example of a non UI CAPTCHA like the <a href="http://www.asp.net/AJAX/AjaxControlToolkit/Samples/NoBot/NoBot.aspx" rel="noreferrer">Nobot</a>  control from Microsoft. I am looking for a CAPTCHA that does not ask the user any question in any form. No riddles, no what's in this image.</p>