These are resources, not necessarily recommendations (though for some tools I've written a glowing review). Some are free and others are free to try then require purchase. Please check them out and decide for yourself if they will work in your classroom.
American Panorama - an atlas of U.S. history through maps
American Social History Project - "...challenges traditional ways that people learn about the past with its print, visual, and multimedia materials that explore the diverse social and cultural histories of the nation."
World Maps - geography online games (Sheppard Software)