The Global Digital Elevation Map was developed from data collected by the Japanese Aster sensor aboard the NASA satellite Terra. Data points are 30M apart and the dataset covers 99% of the earth. For comparison,the Radar Shuttle Topography Mission covered but 80%.
Downloads/Links:
26-megabyte TIF (it will begin drawing on your screen if you click!)
Aster GDEM Page
Search and download (there are warnings heavy demand may mean some restrictions)
- NASA announcement (pdf)
- BBC
- Wired