Classical Atlas Project

The Barrington Atlas is a reference work of the ancient Greeks and Romans, the lands they penetrated, and the peoples and cultures they encountered in Europe, North Africa and Western Asia.
http://www.unc.edu/depts/cl_atlas/

Rome: Map Resources

Maps of the Roman Empire
http://www.dalton.org/groups/rome/RMAPS.html

The Roman Empire

The Roman Empire at its Greatest Extent
http://www.acs.ucalgary.ca/~vandersp/Courses/maps/basicmap.html

Ancient Atlas - About.com

A collection of annotated links for online maps of the ancient world and from antiquity.
http://ancienthistory.about.com/library/bl/bl_maps_index.htm

The Interactive Ancient Mediterranean Project

"IAM: an on-line atlas of the ancient Mediterranean world ... "
http://iam.classics.unc.edu/

Historic Atlas Resource - Europe

Historical and Cultural Atlas Resource
http://darkwing.uoregon.edu/~atlas/europe/maps.html

Perseus Atlas

Map server gateway offering browsable maps of named places from the ancient world. Allows overlays of Roman provinces and modern boundaries, and comparisons against modern features and population centers.
http://www.perseus.tufts.edu/cgi-bin/patlas

Maps and Codices of the Roman Empire

A few maps of parts of Rome and the provinces. With a timeline of the Roman Empire.
http://www.jmiller.demon.co.uk/