You\u2019ve heard public address announcements at public arenas asking parents of lost children to come and pick them up. The Legoland amusement park in Billund, Denmark, is using radio frequency identification (RFID) tags to bring direct communications to that process.At its season-opening day in March, the park launched a new child-tracking system that combines RFID tags and Wi-Fi technology, according to a recent report in Network World. Visiting parents with cell phones and text-messaging capabilities can rent wireless-enabled wristbands for their kids, and then track the children to within about five feet of their location if they become separated.At Legoland, Wi-Fi access points and location receivers scattered throughout the 2.5 million-square-foot park are set to receive Wi-Fi-compatible messages. The access points and receivers pick up Wi-Fi messages from the RFID tags (from a vendor called Bluesoft) and use triangulation to determine where a particular tag is located. Now the whole park doesn\u2019t have to hear that your kid is missing.