RFID (radio-frequency identification) is the wireless non-contact use of radio-frequency electromagnetic fields, for the purposes of identifying and tracking tags attached to objects.
This is the ID-20LA, a very simple to use RFID reader module from ID Innovations. With a built in antenna, the only holdup is the 2mm pin spacing.
Power the module, hold up a 125kHz card, and get a serial string output containing the unique ID of the card.
Note: The new ID-20LA is essentially the same as the older ID-20, but has a lower input voltage.