You can obtain topographical maps, both color & shaded relifes) of the world from here: http://www.ngdc.noaa.gov/seg/topo/globegal.shtml They are made from the world DEM data and can be downloaded in variuos file sizes. Jusy use the grayscale for a bump map and the color one for a texrure and map them to a sphere. These maps are in Mercator projection so should map to sphere OK (they look out of proportion at the poles in this projection, ever try to peel an orange in one piece and lay the skin flat?).