The GADM database of Global Administrative Areas has boundaries for every countr...

The GADM database of Global Administrative Areas has boundaries for every country, in a variety of formats. They're normalized into 4 "layers" IIRC. You can push them straight into postgis or whatever.

http://www.gadm.org/

(Oops, I just realised you're looking for full maps with elevation at each point, and this is just a bunch of polygons. Still a very useful resource.)