I used a shoe ID tag (
http://www.whosshoesid.com/) this past March. We got lots of compliments on it, and thank goodness we didn't have to "use" them. My children are DD2, DD4 and DS8.
It was so nice to just velcro these into their shoe laces and forget them...the kids wore the same shoes to the parks everyday, so we didn't have to remember to put the ID on....it just stayed on their shoes the whole time.
Inside the velcro, was the child's name, parent's name and our cell phone number. It worked really well!!!