Kindercity, a science park for children in Zürich (Switzerland), tags its young visitors with an RFId microchips.

Instead of paper tickets, kids get bracelets on their arrival and as soon as they approach a particular attraction, the bracelet is activated. They are identified, and the price of the entrance is automatically taken from their account (just like an electronic wallet.) So they pay only for the attractions they visit.

Via Nouvo.