There is a modern twist on the ancient game of the scavenger hunt. Geocaching. You get a geocaching unit or use a GPS, sign up for free instructions on the web site for the game, and you can start looking for the hidden stuff planted by people all over the place.
I have lived in the same area for a really long time and never heard of it, even though treasures are just down the street. This game was started up in 2000 after GPS units started being marketed and has really started to spread in popularity. So far, we have gone to five or six hunts right around our town. Some of them are in surprisingly busy places places, and others are more remote. We found one big treasure box at one place where you could take a treasure and leave one for the next person. Some had micro-sized journals left for anyone who found them to sign, and at a few places we found absolutely nothing. It's been fun! We will probably start planting some treasures of our own around eventually.
Have you geocached?