Local maps are generally available for just a few dollars at local bookstores and newsstands. You can get city and custom-made maps online using a number of sites including Google Maps and U.S. Map24. Other sites include The Ultimate Trip Planner, Yahoo! Maps, MapBlast and MapQuest.
Traffic condition maps for major cities are available from MSN Maps and Yahoo! (get the map, then click on "Traffic" icon).
You can plan a route between two locations using U.S. Map24, Mapquest, MapBlast and most of the other mapping sites.
The U.S. Census Bureau posts census-related maps.
You can see aerial photographs of addresses using Google Maps (click on "Satellite").
NationalAtlas.gov lets you custom draws maps of North showing roads, city and county boundaries, pollution sites, demographic information, water use, etc.
Foreign: Google Maps, Map24, Mapquest and MapBlast all cover many foreign countries. Otherwise, search the Internet or call NYPL Premium Services or another large library's document delivery service for a copy of a print map.
Historical: Bell & Howell produces a database of historical Sanborn maps of cities from the 19th and 20th Centuries that is available through many public and academic library web sites. Otherwise, you can call NYPL Premium Services for copies of historical maps.