Stopping Drupal spam registrations without an annoying captcha

There are many modules out there to prevent spam registrations in Drupal, but many of them involve some sort of Captcha, which I hate, or a paid for service. Stopping fake site registrations should not make it harder for the legitimate people trying to register on your site, and having to pay to prevent spam does not sit well with me.While Drupal does have a setting to "Require email validation".....