Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model Version 2 (GDEM V2)
The ASTER Project is a collaboration between Japanese and American researchers from a wide range of scientific fields. The ASTER itself is a "high efficiency optical sensor which covers a wide spectral region from the visible to the thermal infrared by 14 spectral bands." It was launched aboard a satellite in 1999 and is the only digital elevation model (DEM) that covers the entire surface of the earth at high resolution. Version 2 of the data was released in 2011 with full coverage of the earth (84 degrees north latitude and 84 degrees south latitude) with a resolution of 30 meters. More information.
Shuttle Radar Topographic Mission (SRTM)
SRTM was collected in February 2000 with a specially modified radar system that flew on board the Space Shuttle Endeavour. The near-global DEM (60 degrees North latitude and 54 degrees south latitude) has a resolution of 30 metres for the United States but 90 meters for the rest of the world. More Information.