Thanks for all the ideas! I just love the idea of a metal dog/pet tag (metal is neat), but MaryCarly and Monimarine's laminating idea is more reasonable; one could get a lot more information on the tag, and maybe even increase chances of a return versus just listing name and phone number/e-mail ("Hi! My name is Kirsten! If you're reading this, I am lost and very scared. Please return me to Julie at (info) and she will give you a reward!")

At a convention, someone was selling hand-drawn dogtags; I don't know quite how they worked, but I could probably search the Internet for their vendor....