Forget about tattoos. It seems like the new thing to get planted (or implanted) into your skin are RFID chips that can be programmed to allow you to login to your computer with just a wave of your hand in front of an enabled reader. The chips can be implanted by a surgeon or anyone else "qualified" to do it. There seem to be other uses for them, and if you're so interested. I'd rather just write my username and password on a post-it note instead of going through all of this pain just to be a little more technologically "advanced" than others