Have you got a cat or dog? Are you frustrated by the small amount of info you can add to it's collar ID tag or the tiny piece of paper inside the ID tube which always seems to get wet or fade with age even if you wrap it in cling film/Saran wrap first?
Why not attach a small spare flash drive which contains ALL of the pet's details (pet's name, your name, address (map + pictures of your house), all Tel. numbers (mobile and home), email addresses, Skype address, What'sApp account, Facebook account, Twitter account, pet's favourite food, any allergies, dietary requirements, if pet is microchipped or not, birth date, sex, description, neutered or not, pictures of the pet and owners, name and address of vet, etc.).
The flash drive should be waterproof and small, something like the Verbatim Tuff-n-Tiny would do.
If it's for a dog, why not add Easy2Boot and a puppy linux ISO too!