GPS and inexpensive receivers have spawned a whole new sport or hobby called geocaching. A person or group hides a waterproof container containing a log book and some "treasure" items anywhere in the world. The container's latitude and longitude are recorded and posted on one of several geocaching Web sites. Individuals then may use those coordinates to find the cache using their own GPS receiver. When the cache is found, the finder records the details of the discovery in the log book. He may take some of the treasure if he leaves behind equivalent treasure for the next person. Check out www.geocaching.com.