Free map images can be downloaded from these sites.
Note: For unregistered users: You will need to use the Trial version to use these maps, the unregistered Shareware Demo version cannot be used with these images. (The Trial version is included in the OziExplorer Software download.) These maps will require calibrating within OziExplorer using the Load and Calibrate option. (This is described in the Tutorial which can be accessed from the OziExplorer Help Menu).
Free maps and listing of other maps available.
http://www.lib.utexas.edu/maps/americas.html
The Mostly Free DRG Reference Page (Some of the DRG sites also have DEM data download)