There could be various swapping device throughout the mall.. When you visit the mall, you can swap your pass at various places, so the other person in your family can know where you are. At information can be tracked at any swapping display device. This may work effectively without having the need of Cell-phones. It can work perfectly for children, who would love to swap.

When you swipe your pass, and press some button, it can tell when and where other family members last swipped.

It can work various places. Infact the network of such things could be very helpful. It tells that physical location of the person. It can be linked with GSM. The record can be stayed only for intended number of days.