From HacDC Wiki
Katie dissolved one of her SmarTrip cards, and so did Q, giving us a couple of RFID chips that we'd like to hook up to antennae and eventually integrate into something wearable—perhaps a patch or cuff. According to our understanding, the SmarTrip card is an ISO/IEC 14443 Type B card that has a 13.56 MHz operating frequency, 10 cm operating distance (under optimal circumstances), and 106 kbps data transmission rate. This antenna matching-circuit calculation (link not working) and this 13.56 MHz RFID systems and antennas design guide may prove useful.
I wonder if you could work one of those RFID chips into a ring or a cufflink... --The Doctor
Trossen Robotics in Westchester, IL sells a few 13.56MHz RFID Tags that might be useful to dissect and or transplant into. Very similar to a cufflink. I've ordered a few and will see how it works. Right now the Antenna design is the hardest part. How do you get enough power to the chip from an adhoc antenna? rich