The University of Texas at Austin keeps an extensive archive of maps. Also check out their comprehensive links section. (http://www.lib.utexas.edu/Libs/PCL/Map_collection/Map_collection.html)
The Food and Agriculture Organization of the United Nations has created Global Climate Maps which show rainfall, temperature, sunshine fraction, climate classification, and biomass potential for a large number of countries. (http://www.fao.org/waicent/faoinfo/sustdev/EIdirect/climate/EIsp0002.htm)