To what end? You want your card to be internet addressable?

Also, I'm not enthusiastic about trying to communicate an IPv6 address over the phone to the wage slave working at the pizza joint. You'd have to implement one of those address-to-word setups, which would make for some amusing card "numbers". How would you like getting a card with "chinky challis uta ablow wiry rehaul a carotin" on the front?

Something like: http://jubei.ceyah.org/cgi-bin/ipv6toenglish