Fitting the profile

I recently read an article on an Economist article talking about a very smart algorithm written for Tesco to classify their wide assortments of items based on their loyalty customer behavior. Tim Manner (of Reveries.com) has given a good explanation of what it essentially does. The classifications drive the determination of what promotional material gets mailed to you. How many of us have got absolutely mindless coupon/mailers show up at our homes week after week. I would be delighted the day something useful shows up at my house that I am genuinely interested in. I think the sender would command some kind of brand loyalty from me. On the other hand I wont be surprised if the brand image takes a beating if they keep sending useless stuff. One company that has consistently impressed me in terms of presenting the right items through email and their website is Amazon. Wonder what algorithm they use!!!!