GITA, the Geospatial Information & Technology Association has a program called Location in Education where educators can borrow 10-15 GPS units (like the one pictured here), free of charge except for shipping and handling.
The units only work outdoors since they depend on signals from satellites that will give the unit longitude and latitude coordinates. People then can use these units to locate treasures that have been hidden around town. Many libraries already have scavenger hunts and chances are that teens will pick up pretty easily on using these devices. If you have the opportunity, try them out with staff first-they’ll discover how easy and fun they are to use.
It’s possible to create endless tie-ins with literature and get readers involved in books in a different way- if they have the opportunity to almost become a character in the story and help solve a mystery or two that the book might provoke.
Geocaching.com is a great site for resources and developing community contacts for others who geocache. There’s also an app for the iPhone or iPod Touch which will work as its own GPS unit. (As a side note, there’s an article by Christopher Harris, coordinator for a school library system, about every student having an iPhone.) Feel free to share your stories of geocaching at your library.