Maps Online 

Odden's Bookmarks - one of the most comprehensive collections of links on the web relating to maps and mapmaking, old and new. It allows searches for links by keyword or browsing of many different categories, including maps and atlases by region or country.

Historical Maps - an extensive selection broken down by region from the Perry-Castañeda Library Map Collection, University of Texas at Austin. See also its page on other historical map web sites.

Map History/History of Cartography Gateway - an extensive site dedicated to the study of early maps and associated resources and activities, created and maintained by Tony Campbell of the British Library. See also his page on images of early maps on the web.

Cartographic Images - large corpus of historically significant maps arranged by time period (ancient through renaissance), maintained by Jim Seibold.

Antiquarian Maps - nice collection of early map images from the Yale University Library Map Collection, categorized by region.

Antiquarian Maps at Reed College - database of antique map images searchable by date, title, mapmaker, and area.

Map Case - selection of images from the map collections of the Bodleian Library, University of Oxford, with an emphasis on Britain and America.

OSSHE Historical and Cultural Atlas Resource - historical maps and cultural images developed at the University Oregon for pedagogical uses.

Historical Atlas of the 20th Century - political, economic, demographic, religious, and historical maps of the countries and continents over the last century, offered by Matthew White.

The Americas

American Memory Map Collection: 1500-2004 - extensive selection from the Library of Congress Map Collections, focusing on Americana and cartographic treasures.

David Rumsey Collection - large collection of high resolution images, focusing on 18th and 19th-century North and South American cartographic materials, including maps, atlases, globes, and maritime charts.

Hargrett Library Rare Map Collection - maps of America, with an emphasis on Georgia and the South, divided into various categories including new world, colonial America, revolutionary America, and American Civil War.

Canada at Scale: Maps of Our History - National Archives of Canada exhibition of maps reflecting the evolution of cartography in Canada, with sections on government cartography and exploration, colonization, and development.

Europe

IEG-Maps - digital historical maps, mainly showing developments in politics, economy, administration and transportation in Central Europe since 1812, from the Institute for European History in Mainz.

Ravenstein's Atlas des Deutschen Reichs - 1883 atlas of the German Empire with a detailed gazetteer of place names, digitized by the University of Wisconsin-Madison Library.

The Middle East

Walker Collection of Maps of Asia Minor - collection of historic maps, printed from 1511 to 1774, covering Asia Minor and the surrounding areas (the Mediterranean, Middle East, and Balkans), made available by the University of Melbourne Library.

City Maps

Historical City Maps - maps of American and European cities from the Yale University Library Map Collection.

Dutch City Maps - maps from Blaeu's Toonneel der Steden (1652) scanned by George Welling, University of Groningen.

Maps of London - UCLA's Department of Epidemiology offers the Map of London Water Works (1856) and Reynold's Map of London (1859), as well as links to Greenwood's Map of London (1827) and Booth's Map of London Poverty (1889), offered by the Bath Spa University College and University of Michigan respectively.

Maps of Jerusalem - "Jerusalem 3000: Three Millennia of History," a web exhibition of maps and views of Jerusalem presented by the Osher Map Library, University of Southern Maine.