Combining BookCrossing and Geocaching

Two things that are on my "would like to do someday" list combined together, although I'd rather use a topo and maybe an altimeter instead of a GPS, seems like cheating somehow, though I guess they are finicky enough to be a challenge. Also of note to the web designers who read this, how cool is this link shortening technique? http://webpages.charter.net/---/caches.html. much sexier than using CSS overflow: hidden;