Atlapedia Online
Contains full color physical and political maps as well as key facts and statistics on countries of the world.
http://www.atlapedia.com/

Multimap
Global mapping service including street maps of Europe, North America and Australia.
http://www.multimap.com/

TerraFly
Searchable aerial views of cities and towns in the United States.
http://www.terrafly.com/

United Nations: Cartographic Section
General country and special issues maps.
http://www.un.org/Depts/Cartographic/english/htmain.htm

Atlas of the Biosphere
A collection of maps, schematics, and information about human-environment interactions, directed at the education community.
http://www.sage.wisc.edu/atlas/

Maps of World
Online maps showing countries of the world and continents. Too wide for smaller monitors.
http://www.mapsofworld.com/

TerraServer
View maps and aerial photos of various parts of the Earth.
http://terraserver.microsoft.com/

Great Circle Mapper
Shows great circle path between specified points on the globe with an aviation focus.
http://gc.kls2.com/

Readmap Project
Online maps collection with political and economical overview of each country.
http://www.readmap.com/

Google Maps
Provides directions, interactive maps, and satellite/aerial imagery of the United States. Can also search by keyword such as type of business.
http://maps.google.com/

Expedia Maps
Offers searchable listing in the United States and Europe by address and driving directions.
http://maps.expedia.com/

United States Library of Congress Map Collections
Top-level categories include cities and towns, cultural, landscapes, conservation and environment, military battles and campaigns, discovery and exploration, transportation and communication. Searchable by keyword, location, creator, subject, and title.
http://memory.loc.gov/ammem/gmdhtml/

Planet Observer
Displays country and ocean maps, followed by demographic data on each reviewed area.
http://www.maps4free.com/

Map Up
Provides continental, oceanic, and country-specific maps, followed by geopolitical analysis.
http://mapup.com/

ABMaps
Online interactive map of the world, with detailed street atlas for North America.
http://www.abmaps.com/

National Atlas of the United States
U.S. government map portal providing access to many government branches including USGS, Census, U.S. Forest Service, NOAA, National Park Service and others.
http://www.nationalatlas.gov/

Maporama
Generates maps for a desired address or point of interest. Output is also viewable on handheld computers.
http://world.maporama.com/

Windows Live Local
Combines online mapping and local search, uses a scratch pad to take notes, and allows to search questions around the United States in a geographical context.
http://intl.local.live.com/

Fallingrain Global Gazetteer
Look up countries, cities, and airports and obtain topographic maps, weather data, and selected satellite imagery.
http://www.fallingrain.com/world/

Shaded Relief Map of the World
Interactive global map, including topographic relief, satellite imagery, and political information. Includes place finder.
http://www.shaded-relief.com

World Atlas
Get maps and relevant information about every country, every U.S. state and dozens of major American cities.
http://reference.aol.com/atlas

CIA World Factbook - Reference Maps
Various maps of the world in both jpeg and pdf format that are updated annually.
https://www.cia.gov/library/publications/the-world-factbook/docs/refmaps.html

Worldmapper
A collection of world maps, where territories are re-sized on according to the subject of interest.
http://www.worldmapper.org/