RFID

A technology that has been widely encouraged amongst developers, is Radio-Frequency Identification (RFID). RFID is a technology that allows an 'individual identification' system to be incorporated into practically anything.


www.tfl.gov.uk
London's Oyster Cards use RFID

As aforementioned RFID is encouraged by developers, and has been the 'hot topic' for many developer discussions and workshops. Here is a video of some RFID implementations being shown at 2008's Takeaway festival...



This technology is cheap, and could easily be implemented into household objects. RFID technology is also available on the Arduino, so implementation would be a familiar practice and be extremely flexible.