MapsGet maps of anything you want.
Social Studies:
War Sites:
The American RevolutionThis site features aniimated clips, an interactive timeline, other resources and helpful links. 
The Civil WarAll the battles are here, and a timeline is also included.
American/World History:
The History ChannelFind upcoming shows about things you're learning about, and more!
History and Social Studies HelpGet help here.
Modern History Source BookLots of information on modern history.
refdesk.comLike the site says, the single best source for facts.
Women in World History Learn about the women's roles in global history. This site feature, biographies, lessons, and essays.