Learn all about how it works in my new paper, "The Ultra Gleeper: A Recommendation Engine for Web Pages", soon to be a major CodeCon presentation. Of special interest is the "Giving away the store" section, where I do what I wish other people would do and summarize all the little epiphanies that turned into the design/software/idea/whatever.
Have fun. If you start using this, or start writing your own, I'd like to hear what you think. I made an account on my installation for Sumana so hopefully I can get some user feedback from someone who's not me.
Update: I redid the web page to make it more user-level "why you need a recommendation engine" and less academic "why is this recommendation engine different from all other recommendation engines?", since the latter is now well-covered in the paper.