DIVA-GIS

Country level

Download country level data for any country in the world: administrative boundaries, roads, railroads, altitude, land cover, population density.

Global/continental level data

Administrative boundaries for: The world (also includes some rivers and populated places) - the Americas (North America - South America), Asia, Africa See also (the International Taxonomic Database Working Group's world geographical scheme for recording plant distributions).

Global climate data

See WorldClim or diva-gis specific data here

Species occurrence data

GBIF, HerpNET, MaNIS, OBIS, ORNIS, REMIB, SINGER.

Near global 90 meter resolution elevation data

Download

High resolution satellite images (LandSat)

for nearly all of the world can be downloaded here. They are in the MrSid format that can be visualized in DIVA-GIS (note: they are in UTM projections, so you will need to project your shapefiles to UTM as well).

A very good list

of data sources from the Eden project.