CIA World Factbook - Information about 266 countries/world entities. Includes downloadable maps and information about world leaders.
Geocaching: How to Get Started - Get started geocaching with this information from REI.
Google Earth - Use this to go anywhere on Earth. You can also see how places have changed over the years with historical imagery.
National Geographic - Organization founded in 1888 dedicated to promoting education about the Earth.
USGS: Maps, Imagery, and Publications - The U. S. Geological Survey offers free downloadable topographical maps.