Adds CAPTCHA anti-spam methods to WordPress on the comment form, registration form, login, or all. In order to post comments or regiser, users will have to type in the phrase shown on the image. This prevents spam from automated bots. Adds security. Works great with Akismet. Also is fully WPMU and BuddyPress compatible.
Features:

* Configure from Admin panel
* JavaScript is not required
* Valid HTML
* Section 508 and WAI Accessibility Validation.
* Allows Trackbacks and Pingbacks
* Setting to hide the CAPTCHA from logged in users and or admins
* Setting to show the CAPTCHA on the comment form, registration form, login, or all.
* I18n language translation support (see FAQ)

Captcha Image Support:

* Open-source free PHP CAPTCHA library by www.phpcaptcha.org is included
* Abstract background with multi colored, angled, and transparent text
* Arched lines through text
* Generates audible CAPTCHA files in WAV format
* Refresh button to reload captcha if you cannot read it

Requirements/Restrictions:

* Works with WordPress 2.6+, WPMU, and BuddyPress
* PHP 4.0.6 or above with GD2 library support.
* Your theme must have a ID); ?> tag inside your comments.php form. Most themes do. The best place to locate the tag is before the comment textarea, you may want to move it if it is below the comment textarea.

Requires WordPress Version: 2.6 or higher

More Details and Download

Thanks,

Shane G.