Educaching: http://educaching.com/
Meet Mr. Swingle: GPS lesson plans: http://sites.arnold.k12.ne.us/gswingle/stories/storyReader$420
Groundspeak Forum: GPS in education: http://forums.groundspeak.com/GC/index.php?showforum=12
USGS Education: GPS, Maps and Compass: http://education.usgs.gov/common/lessons/gps.html
NOVA Online: Lost at Sea... the search for Longitude: http://www.pbs.org/wgbh/nova/longitude/
GPS & Place-based Learning: http://eduscapes.com/omrp/gps.htm
Dr. Christie's GPS and Geocaching Guide for Educators: http://www.alicechristie.org/geocaching/
GPS in the Classroom: http://www.water.ca.gov/watershedrestoration/educationalmaterials/gps_class/index.cfm
Earthcaching Educators Guide: http://www.geosociety.org/Earthcache/WebBook/EarthCaching_EducatorsGuide.pdf
Earthcache Sites for Teachers: MICHIGAN
Garmin GPS Guides for beginners: http://www8.garmin.com/aboutGPS/manual.html
Geocaching Resources: http://www.geocaching.com/resources/default.aspx

An Introduction to Geocaching PowerPoint: http://www.geocaching.com/resources/intro.aspx
PDF of the presentation: