You may also want to mention in your post what languages and frameworks you're already using. If you have a java, scala, or clojure backend, using Mahout to ma

You may also want to mention in your post what languages and frameworks you're already using. If you have a java, scala, or clojure backend, using Mahout to make item to item recommendations is pretty simple to do. If you have a different language, I would just look into libraries for collaborative filtering in that language.