Did you know that, according to Kashmir Hill at Forbes, Facebook is Tracking What Users Buy in Stores to See Whether its Ads Work? How? It has partnered with Datalogix, a Colorado based company that gathers information generated by loyalty cards. You know, those cards that you give the cashier at places like Jewel and Walgreens in order to get special discounts or rebates. So, by comparing e-mail and home address information, Facebook can now tell its advertisers how many of its users who viewed their ad actually purchased the product. It claims that it does not gather an individual's purchase history; but only product data, however. The Electronic Freedom Foundation has delved deeper into the data collection from loyalty cards and provides instructions for opting out of the collection process in its blog: A Deep Dive into Facebook and Datalogix: What's Actually Getting Shared and How You Can Opt Out.