3D objects-based CAPTCHA to get rid of spam in comments.
With this plugin you can easily install and use Ironclad CAPTCHA in your WordPress blog. 3D captcha renders several intersecting colored and rotated objects and asks user to count objects of some type. Humans can easily do it (much easier than read twisted text) and bots can't do it at all and never will. Moreover, this captcha stops even spammers with human-based recognition of captchas, as Ironclad CAPTCHA has very unusual answer entering process. Just install the plugin, register and get API key on the official site (for free) and forget about spam forever.