GIS Day is upon us tomorrow November 15th. This day coincides with National Geography Awareness Week. For all the educators our there, the resources are bountiful.
Some great ones are listed here:
ESRI
http://www.esri.com/industries/k-12/education/gaw.html
Google
http://www.google.com/educators/gaw.html
National Geographic's Mapmachine
http://plasma.nationalgeographic.com/mapmachine/index.html
My Wonderful World (.org)
http://www9.nationalgeographic.com/mywonderfulworld/docs/