CaptchaThis! is an attempt to further the fight against comment spam. The idea is asking the user (or robot, for that matter) to ‘recognize the meaning of a question and answer it. The plugin has two modes: “Click The Image” and “Answer The Question”.
SEO Siloing WordPress plugin allows bloggers to configure blogs that follow the “SEO siloing” technique where posts are grouped by category and cross-category links are only made to special category landing pages.
wp-ajax-newsletter is a WordPress plugin that allows users to subscribe and receive a newsletter containing the blog latest posts.