National Geographic
This is the home page of the National Geographic Magazine.
Atlapedia
Atlapedia has great maps and detailed information about every country.
CIA World Factbook
The CIA's World Factbook contains details of the geography, government, etc. of just about every country and territory in the world.
Getty Thesaurus of Geographic Names
This quick reference site can explain the location and brief history of a geographic name.
 Exploring Maps
This page has lessons on using maps.
Flags of the World
This quick reference site shows the flags of every country and explains how they are properly displayed and what regulations about the flag exist in each country.
MapQuest
MapQuest allows you to freely create maps showing driving routes in the United States from one destination to another.  There is also an interactive atlas that allows students to find any place using a large database of worldwide maps.