Ancient World Mapping Center
Interactive Map of the Roman World (works best in Chrome & Safari). Old version of the site here.
CIA World Factbook
Historical Atlas of the 20th Century
Internet Resources for Geographers
Perry Castaneda Library (PCL) Map Collection at University of Texas
PCL Outline Maps
Water Risk Atlas
22 Maps that Show Regional (US) Speech Differences
Linguistic Maps - MuturZikin