@Tim-right, the chips on credit cards are flat, but much bigger than cat/dog chips, which are much smaller than a grain of rice. Personally, the chips I prefer are of the Kettle variety, with salt & pepper. Definitely avoid the cow variety :-p
I recall Target promoting a chip card years ago. They even mailed me a special card reader -- I don't recall if it was to make online payments simple, or if they thought I was a retailer (I'm not) who might embrace the new technology. I never unpacked the device and it's probably still around the house somewhere.
With technology, who knows where surgical implantation of some kind of electronic devices might lead in the future? Hopefully the recipient would be aware of, and agreeable to, its insertion, if things ever came to that. Back to the payment thing, it would certainly be convenient for travelers, although temporarily expensive for some retailers and credit card issuers, if all cards and processing systems were compatible.