David Rumsey Map Collection
Thousands of historic and rare maps in high resolution
Old Maps Online
Search or browse across multiple historical collections by geography and date
Alexandria Digital Library, from UC
Includes link to international as well as U.S. data sources.
Perry-Castañeda Library Map Collection
University of Texas at Austin's large collection of digital maps from around the world
Ancient World Mapping Center
Cartography and GIS within the field of ancient studies
Introduction to GIS
Includes how to get the software, manuals, tutorials; from Amherst IT.
Infomine: Maps and GIS
Searchable, with links to thousands of resources
National Map (USGS)
Public access to high quality geospatial data from consortium of federal, state, and local partner
Atlas of the Biosphere
Downloadable data/maps about the environment, including land use, human impacts, ecosystems, and water resources.
National Geologic Map Database
Print and digital U.S. geologic maps, many with downloadable data.
EROS (Earth Resource Observation Systems), from USGS
Data management, systems development, and research field center for USGS National Mapping Division