Protect Your Rails Application Against Spam with Akismet
Austrian development agency, Sparkling Studios, look at how to use the Akismet anti-spam system to check data submitted to your site and protect your application from spam. It works by signing up for a key from Akismet and using a Ruby Akismet library. Then whenever you want to check your data, you make a simple call and Akismet returns a true or false based on whether the system believes the data to be spam.
It should be noted that this method is primarily useful for blog comment and trackback related spam, but could be useful on other data that fits the same structure.