This plugin makes it easy to add a Bayesian classifier to your models.

Consider a scenario where you have a blog, and you want to prevent spam comments, but don't want to use captcha as they are bad from accessibility standpoint. What is the solution, in steps 'actsas_classifiable'. Use a Bayesian classifier to distinguish between spam and non-spam and if the comment is flagged as a spam, use a captcha based solution or reject it. Or maybe you want to track the preferences of each user and then based on that make suggestions to them. 'actsas_classifiable' can help in both scenarios and several other.