And why the hell not:
It's a series of implantable surgical steel, titanium, or medical plastic that's placed under the skin. The tattoo can then be read via touch. Subdermal implants are nothing new, but using them to create body art for the visually impaired is an interesting idea. Klara Jirkova thinks the implants could be used in the divet between thumb and pointer finger, so when people shake hands they can "read" each other's names and info.
More here.