CAPTCHA links

I was looking at using some type of image verification on my website.   Here are some links with information about 'CAPTCHA'.   Please pass along your tips and tricks when using this technology to stop spam bots, comment spam bots and other automated tools to submit information to your site.

        Stopping Automated Web Robots Visiting ASP/ASP.NET Websites
        http://tinyurl.com/y8swha

        What is CAPTCHA?
        http://www.captcha.net/

• http://www.webopedia.com/TERM/C/CAPTCHA.html
• http://www.codeproject.com/aspnet/CaptchaImage.asp
• http://www.aspnetworld.com/articles/2004030101.aspx

Tx,

Steve