Many of us now have smart phones and for those that have a (free) QR reader application you will know about the square 2D bar codes that are around. Here is a new type of pet ID tag that contains more than just Fido's name and phone number. Scan the tag with your QR app and it will bring up Fido's web profile containing, contact information for his owners including phone, email, FB, Twitter etc. Also vet information such as contact details, current medications, allergies, vaccinations and microchip number. YOU control how much information is visible.
Take a look at the FurCode tag at http://furcode.com/aff#oid=1018_5
For those with foster animals, the profile can be changed as your fosters come and go. FurCode supports rescues and shelters, discounts are given for multiple tags.