In May of 2000, by presidential order the Selective Availability feature of the GPS satellite was turned off, and consumer level GPS hardware the world over suddenly became much more accurate.
Fairly soon afterwards, a new sport was born: geocaching. The basic idea is that individuals place small boxes containing log books at various places and record their position using a GPS. These positions are then recorded at geocaching.com, a central website. Other geocachers can then find caches near their location, and try to locate the cache in a kind of high tech treasure hunt.
It's fun, and a great excuse to get out and do a bit of hiking, especially for us couch potatos. My wife and I have created two caches, and visited a few more, and plan to do more in the future.