Biohacking
Biohacking is a way to 'enhance' your body with technological devices.
The most famous hack is probably from Neil Harbisson who had an antenna implanted at the top of his skull. Neil was born colorblind, but with the antenna he can "hear" colors. Check out this YouTube video for an interview with Neil.
Other people add magnets to their fingers, so they can perceive magnetic waves.
Yet others put LEDs under their skin. Check out this article for more information.
Technically speaking a RFID chip (radio-frequency identification) falls into this category as well. People use them to open doors, etc. It is interesting to know that a RFID chip can not be used to track your whereabouts. Special scanners only work at close range.
The illuminati are on record of saying that they want everybody chipped, and that if someone doesn't "fit in" they will simply turn the chip off (no more money, etc).
The RFID chip is not the mark of the beast.