CGIAR World Digital Elevation Model
The CGIAR-CSI SRTM 90m DEM dataset is a processed distribution of NASA's excellent worldwide elevation data. Unlike many other datasets, it's high resolution, worldwide in coverage, and processed to eliminate voids in the data.
This drive contains all individual raw files for the world elevation model, as well as a merged world elevation model and world hillshades in native and web mercator projections. Included are license and readme documents. This dataset is distributed under its original license.
OSM Planet
OpenStreetMap is a free editable map of the whole world that allows users to view, edit and use geographical data in a collaborative way from anywhere on Earth.
This database, usable for tile rendering, map servers, analysis, and visualization, is the OpenStreetMap planet (Planet.osm) in a database cluster: thus it can easily be attached as a new database (including PostGIS language extensions) to any system with Postgres 8.3.
TIGER US Census Data
This data set is a complete set of Census 2000 and Current shapefiles for American states, counties, subdivisions, districts, places, and areas. The data is available as shapefiles suitable for use in GIS, along with their associated metadata. The official source of this data is the US Census Bureau, Geography Division.