Animated Atlas of African History 1879-2002. Interactive map developed at Brown University by the Instructional Technology Groups' Summer Institute in conjunction with Professor Nancy Jacob's course on Twentieth-Century Africa.
David Rumsey Map Collection. Large collection of digitized historical atlases.
Historic Cities. Maps, documents, literature and more.
Map History/History of Cartography. "THE Gateway to the Subject."
Mapiversaries. "An endeavor of the map collection at the University of Iowa." Tumblr featuring historical maps.
Maps of Delaware and the Mid-Atlantic Region. From University of Delaware Library.
Merian Map of Paris (1615). Images on Wikipedia page.
Motco UK Directory and Image Database: Antique Maps, Prints & Books relating to the city of London.
New Jersey Historical Maps. From Rutgers University.
Oregon Maps: from Oregon State University Libraries.
Paris in the 19th Century. Maps and views from the University of Chicago Library's Map Collection.
Perry-Castañeda Library Map Collection. Also includes links to web resources. From the University of Texas.
Places & Spaces: Mapping Science. "Maps for tracking human activity and scientific progress on a global scale." Interesting and sometimes beautiful visualizations.
Sanborn Fire Insurance Maps from Georgia Towns and Cities. From the Digital Library of Georgia.
Sanborn Fire Insurance Maps of Florida. From University of Florida Digital Collections.
Sanborn Fire Insurance Maps of South Carolina. From the University of South Carolina Libraries Digital Collections.
Turgot Map of Paris (1734-1736): Images on Wikipedia page. Highly detailed - one can zoom in to see individual buildings.