Global Land One-kilometre Base Elevation (GLOBE).
GLOBE is an internationally designed, developed, and independently peer-reviewed global digital elevation model (DEM), at a latitude-longitude grid spacing of 30 arc-seconds (1 Km).
The ongoing project makes use of several data sources to attain high data quality. Important parts were taken from GTOPO30, but there are also additional contributions not part of GTOPO30.
GLOBE provides data sets of two levels of quality: G.O.O.D. (Globally Only Open-access Data, unrestricted use) and B.A.D. (Best Available Data, restricted use for some regions).
More information on these issues and the data set in general can be obtained from Online Documentation v1.0.