Matthew Inman of the famous webcomic The Oatmeal has a great idea: make it a common custom for cat owners to give their indoor cats orange colors--and no other color. That way, if you ever see a cat outdoors wearing prison orange, then you know that it's a lost cat.
Inman is trying to address a problem: although 26% of lost dogs are returned home, fewer than 5% of lost cats are. That's because cats are good at hiding and most people, if they see a loose cat, just assume that it's an outdoor cat with a human family.
-via Laughing Squid