Old Maps Online
Finally, federated searching for digitized historic maps! Allows the user to search for digitized historical maps across many different academic and research collections.
NYPL Map Warper
Registered users of the map warper can georectify digitized maps from the NYPL collection and export them as KML files for use in a GIS or other geotechnologies. Registration is free and all are welcome to participate.
David Rumsey Historical Map Collection
Over 33,000 digitized historical maps online, free and open to the public.
University of Texas
About 44,000 current and historical digitized maps from around the world; most are in the public domain.
A crowd-sourced effort to georeference historical maps of the UK.
Historical Maps and Charts
Over 35,000 digitized maps and nautical charts from NOAA, all in the public domain and free to download as .jpg files.