Dennis Krul

I installed a reCaptcha plugin for WordPress, which allows people to directly comment on my posts without having to register for an account first. Should be effective against spammers, who (despite the fact that they had to register for an account) were spamming my moderation queue.
If you also happen to run WordPress I highly recommend it! Simply sign up for an API key, drop the files in your plugin directory and enable the plugin from the admin interface. As an added bonus you help to digitize books (Did I mention it is free?)