I didn't know if i should post this in Weapons or here, but i think it fits here better. It's scary, next time you think you got a bug bite it may be something else. Don't forget RFID tags can be as small as a grain of pepper, or fine powder.
EDIT: Found some info on the maker...
LINK
Apparently a Danish company called Empire North is working on ID Sniper, a sniper rifle that can implant a GPS chip in your body from up to 1.1 Km away.
  It is used to implant a GPS-microchip in the body of a human being, using a high powered sniper rifle as the long distance injector. The microchip will enter the body and stay there, causing no internal damage, and only a very small amount of physical pain to the target. It will feel like a mosquito-bite lasting a fraction of a second. At the same time a digital camcorder with a zoom-lense fitted within the scope will take a high-resolution picture of the target. This picture will be stored on a memory card for later image-analysis.

EDIT: Found some info on the maker...
LINK