Earth Explorer: 3d Earth topography map reference program

I came across this program when I was looking for a good topographic map of the Earth. The free version of this program was exactly what I needed. I recommend it to anyone who is attempting to make Earth-based CIV4 scenario maps.

http://www.motherplanet.net/g_Map_Photo_Satellite.html

There is also the Google Earth map:
http://earth.google.com/
I highly recommend this program too.

Here is an excellent reference of the world's biome regions:

http://soils.usda.gov/use/worldsoils/mapindex/biomes.html

The webpage features a very high-resolution BMP map!