Free sources of topographics maps (see list below)
With Natural Scene Designer, you can view a topographic map from any viewpoint in 3D!
Also creates realistic pictures, fly through animations, and shaded relief map backgrounds.
Click here to find out more
Topographic Map (DRG) and GIS Data Sources for all 50 US States
This is a list of online sources for Digital Topographic Maps. When combined with Digital Elevation Models they can be used with Natural Scene Designer to create pictures like the one above
Note: Some websites refer to Topographic Maps as 'DRGs'.