The basic concept behind the Link Child Locater device, designed by Dcontinuum, is that a parent, guardian or babysitter can use it to locate or keep track of children in crowded locations. The device consists of two components: a bracelet worn by the child, which has an embedded transmitter module that works at a range of up to 100 feet, and a watch-style bracelet which is worn by the guardian. This latter component receives the signals from the children and indicates their direction and their estimated distance on a small LCD display.

I think this would be a very useful device since the incidence of children getting separated from their caretakers in crowded areas is a very common occurrence. However, I would have named the bracelet “no child left behind,” but I think that's already taken.