We tag our kids, and they're 9 and 6- well 6 and 8 last time we were at Disney. We had dog tags ( as in military tags not collar tags like Fido wears! ) made. They actually wear them any time we're away for the day- habit I guess. They don't really need them anymore, both of them know all of their information, but they like wearing them and like I said- habit. The tags have their names, address, and dh and mine cell phone numbers. I also know people who write their phone numbers in sharpie on their child's leg. I have another friend who made bracelets with her cell phone number in beads on it. I don't think it's an issue of being vigilant in watching, it's the people who think it won't happen to them who lose their kids I think. I also think that children who know their information can easily panic and not be able to tell..better safe than sorry.