I wanted to implement a simple captcha for for article comments on a site. And by simple, I mean both in aesthetics and in functionality. After looking around, I found this post that described how you could implement a plugin called Simple Captcha in 10 minutes or less.

The plugin requires RMagick and ImageMagick which takes a little while to install.  So if you don’t have those, then the title of the post probably won’t hold true for you.  After you have everything installed, it takes one line of code in your view and one line of code in your controller to implement the captcha.

Just what I was looking for!