As a gift for his girlfriend, Mike Buss came up with a clever type of box that was inspired by the reverse-geocaching projects that are popular. However instead of the box unlocking itself when located in a certain position, Mike's example is unlocked by the use of a simple RFID reader and a micro servo for the locking mechanism.
We really like the use of an existing commercial product for the box, and the modifications don't lessen the effect. And Mike has also designed a failsafe for the box in case the battery runs flat - there is a "secret" point to apply power and open the box again. Very clever. Finally the box is demonstrated in the video below: