Niņo had a Home Again chip implanted when we adopted him. I don't think I'd ever have a dog, or even a horse for that matter without a chip. It's just not worth the extra few bucks NOT to do it.

A good family friend found a cat wandering and took him in, he had a chip and so she was able to contact the original owner of several years ago. Turns out he's given the cat up, and the newer "owners" didn't want him, so now she has Joque and doesn't have to worry weather there's a family missing him.