Mighty-CAPTCHA add an authentication with Google reCAPTCHA technology to login, comment, and register form, with API keys which delivered by Google.
Simple Email Form creates a simple email contact form to your WordPress site.
NURCaptcha inserts a reCAPTCHA on the Register Form of your site to protect it against spambots.
Asks commenters to complete a simple CAPTCHA if a spam detection plugin thinks their comment is spam. Currently supports Akismet and TypePad AntiSpam.
The contact form plugin with dynamic fields, reCAPTCHA and other features that makes it easy to add custom contact form on your site in a few clicks
reCAPTCHA in WP comments form is an ANTISPAM tool that adds a Google reCAPTCHA to the comments form and protects your site from the spam robots threats.
Recapture fights user registration spam by placing a reCAPTCHA on the user registration form.
Asks commenters to complete a simple CAPTCHA if they don't have a previously approved comment, or if Akismet thinks their comment is spam.
Main configuration page.