In the end, we realized that the best way to give users what they wanted was to crowdsource data from them. At first, we did what Amazon did. Using a process called “collaborative filtering,” Amazon would suggest products to you based on common buying patterns. They still do this. Essentially, if you buy a wrench from Amazon, it groups you with other users who have bought a wrench, and then suggests that you buy other things that they’ve bought.
Excellent description of collaborative filering follows.
