Does anyone here use geocaching.com?
Geocaching is a high-tech treasure hunting game played throughout the world by adventure seekers equipped with GPS devices. The basic idea is to locate hidden containers, called geocaches, outdoors and then share your experiences online.
You look up the coordinates of a geocache on the site, then use a GPS to find it. It's usually an ammo box out in the forest somewhere with a log book and some coins or small objects that you can take and drop off at other geocaches. Everything gets logged on geocaching.com and you can track objects that you leave in geocaches to see where in the world they end up. At the moment there are 767,628 active caches around the world.
I've gone a couple of times and it's a good excuse to go out for a walk, maybe a little off the beaten track...