NASA and Japan’s Ministry of Economy, Trade and Industry released yesterday a new and improved version of their ASTER global digital elevation model (GDEM) which was first released in 2009. This new and improved version offers improved spatial resolution, horizontal and vertical accuracies, and more realistic coverage over water bodies with the ability to identify water bodies as small as 1 km in diameter. This new data is now comparable to NASA's Shuttle Radar Topography Mission DEM data. The new ASTER GDEM covers 99 percent of the Earth’s landmass at 30 meter spatial resolution. It is free to download here. For information on the improved version see here and here.