Bouncy Maps - Cartograms allowing the user to transform world maps to show how large countries would be if a criteria other than area were the key.
David Rumsey Historical Maps Collection - over 100,000 maps and related images browseable online, including rare 16th through 21st century maps of the countries, continents, and the world.
Map History - Online history of maps and cartography from the former Maps Librarian of the British Library in London.
Map Projections - A gallery of black and white pdf printable map projections sorted by type.
U.S. Color Landform Atlas - Images of US states: shaded relief, false-color satellite view, and maps from an 1895 atlas.
Earth and Moon Viewer - Switzerland's Fourmilab presents views of the Earth, Moon, and Solar System.
The National Map - USGS "Topographic Information for the Nation" project, including topographic maps and GIS data for elevation, hydrography, watersheds, geographic names, orthoimagery, governmental units/boundaries, transportation, and land cover.
Real-Time Traffic Maps
Iteris - Real-time traffic maps for various locations in the US.