CIA World Factbook Reference Maps
Various maps of the world in both jpeg and pdf format that are updated annually.

EPA Search your community
Enter a zip code and search an area for environmental information and data.

Geodata.gov
Billed as the "one stop for finding and using geographic data" Find a map, make a map, or browse community information.

Maps Collections 1500-2004
The Library of Congress' Memory searchable collection of maps around the world.

National Atlas.gov
It contains an online map maker, dynamic maps, printable maps, articles.