RFID Powder

http://www.engadget.com/2007/02/14/hitachis-rfid-powder-freaks-us-the-heck-out/

The new chips are 64 times smaller than the previous record holder, the 0.4mm x 0.4mm mu-chips, and nine times smaller than Hitachi’s last year prototype, and yet still make room for a 128-bit ROM that can store a unique 38-digit ID number.

yeah, that freaks me out a little, too!