This is a fun site to view. Plug-in links available at site.
Exobiology is highlighted.
Plenty of details, but hard to read because of background patterning. Brief descriptions available, sometimes with downloadable maps. Provided by the planetary data system, this map is based upon the viking images. Creating a mosaic from the Viking photographs, this site allows reasonably detailed observations of the Martian surface to be made. The Geology of Mars Thomas, Mutch.