I just came across this site called geocaching.com. This looks like a lot of fun! Basically, you use your GPS to go "treasure hunting" for these boxes people leave around. In them, they leave a log book as well as different items. When you find a cache, you log your visit, and you can swap out any item(s) for other item(s).

Makes me want to go out and get a GPS unit. Anybody have suggestions on good units that are decently priced?