I've found a new pastime to try, Letterboxing. From the FAQ:

Here's the basic idea: Someone hides a waterproof box somewhere (in a beautiful, interesting, or remote location) containing at least a logbook and a carved rubber stamp. The hider then usually writes directions to the box, which can be straightforward, cryptic, or any degree in between. Selecting a location and writing the clues is one aspect of the art.

Once the clues are written, hunters attempt to find the box. In addition to the clue and any maps or tools needed to solve it, the hunter should carry at least a pencil, his personal rubber stamp, an inkpad, and his personal logbook. When the hunter successfully deciphers the clue and finds the box, he stamps the logbook in the box with his personal stamp, and stamps his personal logbook with the box's stamp. The box's logbook keeps a record of all its visitors, and the hunters keep a record of all the boxes they have found, in their personal logbooks.

It's appealing to me because it's a goal-oriented (yet still basically pointless), it's a nice weekend outing with my wife and daughter, and it's a modest way to get a little more exercise.

My big beef with the site is that there's no entry for District of Columbia on the directory of clues. Repeat after me:

Washington, DC is not part of Maryland.
Washington, DC is not part of Maryland.
Washington, DC is not part of Maryland.
Washington, DC is not part of Maryland.
Washington, DC is not part of Maryland.

On a UI note, the Letterboxing North America web site has one of the most creative uses I've seen of image map navigation, particularly the page about their mailing list.