The same way dogs have a microchip implant with meta, medical information, we humans will have a microchip implant before not too long. In Spain for example an ID card is mandatory for every adult; recently this ID contains a chip with certain information. It's not difficult to imagine that in the future we'll have this chip implanted as animals, instead of carrying it in our ID card.
It could contain ID info, medical info, etc. If we have an accident a doctor with a scanner could have instant info about our blood type, alergies, etc. If we go into an airport we would be instantly IDed (along with our flight info, which could be included in a Passbook like app inside the chip), so we could go through the controls much quicker.
Actually there is already an extensive Wikipedia page about the subject: Microchip implant (human)