RFID (Radio Frequency ID) chips are slowly being rolled out and will eventually replace the bar-code. Here's a little representation of how it can eventually affect our personal liberties. For more information, I highly recommend the book "Spychips" by Katherine Albrecht. Here are a pair of patents which you can google yourself: Patent#20020165758: IBM - IDENTIFICATION AND TRACKING OF PERSONS USING RFID-TAGGED ITEMS. Patent#6659344: NCR - AUTOMATED MONITORING OF ACTIVITY OF SHOPPERS IN A MARKET.