Take a look at Amazon’s US patent 6865546. This is a patent for a system that determines a buyer’s age according to previous buying records. The patent states that:
One embodiment of the present invention is a system and method of determining the age of an item recipient, such as a gift recipient. The age range for the gift recipient is estimated based at least in part on a customer order history of gifts purchased by the customer for the gift recipient. At a first date, a customer order for a first gift for the recipient is received, where the first gift is associated with a first age appropriateness designation. At a second date, a customer order for a second gift for the recipient is received, where the second gift is associated with a second age appropriateness designation. An age range associated with the recipient is then estimated based upon at least the first age appropriateness designation and the second age appropriateness designation.
I would like to know the “age appropriateness designation” for my recent purchases. Let’s see, I have purchased Cowboy Bebop, Hack//Sign, Neon Genesis Evangelion and Star Wars Knights of the Old Republic II. I bet the system would say that I am a 16 year old geek.