Pocket PC Thoughts has an article about Geocaching and how modern technologies converge to help treasure hunters.
"The current "sport" of geocaching is a convergence of several different technologies and past-times.
Letterboxing started back in 1854, when an Englishman named James Perrot stuck his calling card in a bottle and hid it under a pile of rocks on the shore of Cranmere Pool in Dartmoor. He did this mainly to prove that he'd been there and, given the harsh, boggy terrain, it was certainly something of an accomplishment. Other walkers in the area heard about it, and started placing their calling cards in the bottle to prove that they'd been there too.
The idea spread and now has adherents in many different countries and continents. Unfortunately for gadget freaks, letterboxing is just about as old school as it gets. Using maps, clues and a compass, letterboxers ferret out the location of letterboxes in pursuit of rubber stamps placed in the boxes. When a letterbox is found, the finder inks the stamp and stamps their personal letterboxing book as a trophy.
While getting the stamp is certainly the end result, I think that most letterboxers would agree that the real reward is the journey to reach the letterbox, as they are usually placed in interesting locations one would normally never see."
Fortunately, as proud owners of Pocket PCs, we have a few options open to us that aren't available to the typical geocacher with a monochrome Garmin. For example, my wife and I recently went to Mammoth Lakes, CA for vacation. Before leaving, I located 46 different caches within a 20 mile radius of our cabin. I wanted an easy way to access specific information, including hints and satellite photos. I decided that the best way to do this would be to create an HTML page that would be readable in Pocket Internet Explorer. It wasn't very hard to do, and as it turned out, it was extremely useful to me to have the cache information in this format when I was out in the middle of nowhere."