A Geocaching charm is the treasure you leave in the caches attached with a laminated tiny card with your information! Most caches are quite small, so finding treasures around your home can be hard. The treasure I make will last, and it looks like treasure. I even use swarovski crystal in my creations. Travel bugs and geocoins are things people also use, but the cost for each is quite high. Some of my treasures work out be be as low as 2$ each.
http://amandamackay.com for more samples!