(CIDA) World Maps - Interactive world maps focusing on international development, science and culture.

Google Maps...just keeps adding great features, yet it still doesn't feel bloated in the least. The service offers driving directions, satellite views, street views, business and restaurant locators, user-created maps, public transit routes—the list goes on.

Historical Atlas of the Twentieth Century - A comprehensive set of Historical Maps and Timelines.

NEW Learner.org offers a collection of map-based lessons and an interactive map about the United States. After completing the map-based lessons and trying the interactive map, students can test their knowledge with a short quiz. The map-based lessons include content about Native Americans, the 50 states, colonists, and westward expansion.

Live Search Maps ...Microsoft's Virtual Earth tool keeps the battle for map innovation raging. Street maps and satellite images are almost old hat when you have bird's-eye views from multiple vantage points, plus 3D views that you can navigate like a flight simulation of the real world. Just be sure to use IE to get the 3D ActiveX control. The location finder pinpoints where you are if you have a Wi-Fi-enabled laptop.
Map Machine/nationalgeographic - Huge variety of maps and mapping tools.
maporama - From just an address, you get a complete interactive Maporama map! Maporama is the first European actor of maps online to propose detailed coverage of Europe, the U.S.A., and Canada. Maporama proposes more than 635,000 cities in more than 180 countries.

Maps: Finding Our Place In The World...Learn more about maps and mapmaking as you explore

Maps-of-War presents a special list of the best multimedia war maps from across the world wide web.

MetaCarta provides all of the current news stories that a Social Studies/ Current Events teacher needs along with a geographic context for each story. You could use the idea of MetaCarta to have your students create their own mashup of news stories that they read in class.
Outline Maps - Great outline maps - a must for social studies teachers.
Perry-Castañeda Library - Online Maps of Current Interest:Afghanistan Maps, India Maps and Pakistan, Philippines & Somalia Maps. Online Maps of General Interest; Historical Maps

Placeopedia is a website that provides additional context for Wikipedia entries through Google Maps. Placeopedia connects Wikipedia articles with their locations. Click on any placemark on Placeopedia's map and you will be linked to a Wikipedia article about that place.

Places & Spaces... because information doesn’t have to be boring. They have a really interesting gallery of maps the cover traditional geographic information as well as concept and domain styles
TopoZone - lets you create custom topographic maps and download them right to your desktop. You can make maps to your specifications any time and any place you need them

World Atlas.com... Has them all....terrific site!!!...with great links to additional info.