CleanTalk - Spam protection for WordPress, Joomla, Drupal, and any other websites
SpamCop - Beware of cheap imitations! SpamCop has been protecting the internet community since 1998.
StopForumSpam - StopForumSpam - a database of known forum and blog spam, its sources and the email addresses reported
CheckURL.org - Easily check is your website/url blacklisted
Mollom - Mollom is a freemium web service to get rid of spam, unwanted content and fake users on your...
Antispam Bee - Say Goodbye to comment spam on your WordPress blog or website.