The best collections of Virginia maps are at the Virginia Historical Society and the Library of Virginia. A detailed list of the maps at these libraries is:
Sames, James W., III. Index of Kentucky and Virginia Maps, 1562 to 1900. Frankfurt, Kentucky: Kentucky Historical Society, 1976. (Family History Library book 976 E7s.)
Extensive map collections are at the University of Virginia, Virginia Polytechnic Institute and State University, and George Mason University. The U.S. Geological Survey office at Reston and the U.S. Army Corps of Engineers at Norfolk also have Virginia maps.
Excellent reproductions of Virginia maps are found in:
Stephenson, Richard W. The Cartography of Northern Virginia: Facsimile Reproductions of Maps Dating From 1608 to 1915. Fairfax, Virginia: Fairfax County, Virginia, 1981. (Family History Library book Q 975.5 E7s.)
Atlases and land ownership maps are available for many counties and larger cities at the Library of Congress (see the United States Research Outline) and at other large libraries.
United States Census Bureau State and County Map. This map will allow you to zoom in on any state or county in the United States and read the names of all of the neighboring counties.
The Family History Library has some individual maps and the following atlases:
Hale, John S. A Historical Atlas of Colonial Virginia. [Staunton, Virginia]: Old Dominion Publications, 1978. (Family History Library book 975.5 E7hj)
County Maps, January 1, 1977. Richmond, Virginia: Virginia Department of Highways and Transportation, 1977. (Family History Library book 975.5 E7v)
Doran, Michael F. Atlas of County Boundary Changes in Virginia, 1634-1895. Scale [ca. 1:190,000]. Athens, Georgia: Iberian Publishing, 1987. (Family History Library Atlas 975.5 E7d)
The Family History Library also has city ward maps for Richmond, Virginia for 1809, 1848, 1873, and 1877 (Family History Library film 1377700; fiche 6016750-53). These are helpful when using census records.
Printable maps are also available from the National Atlas of the United States -- http://nationalatlas.gov/printable.html