Geocaching is getting very popular. AJ and Brian sent in this cool Geocache Box they built with Invisible Infrared LED inside. This box has a secret number that can only be seen with a bit of ingenuity, in this case since the numbers are shown with IR LEDs the numbers are not visible to the naked eye. But if you look at it through the viewfinder of camcorder or digital camera and you will see the numbers magically appear.