The level of customer tracking at Amazon.com is another best-of-breed system. Using the data it collects on every registered user during every visit to the Web site, Amazon points users to products they might actually be glad to discover -- and buy. Amazon recommends products that are:
• similar to what you're currently searching for (on-the-fly recommendations that use up tons of processing power)
• related to what you've searched for or clicked on at any time in the past
• purchased by other people who've searched for what you're searching for or have bought what you've bought
You can even customize the recommendations by giving Amazon more information about yourself and your interests and rating the products you've already purchased.