The Center for International Earth Science Information Network (CIESIN) is a centre within the Earth Institute at Columbia University (Link). CIESIN works at the intersection of the social, natural, and information sciences, and specializes in on-line data and information management, spatial data integration and training, and interdisciplinary research related to human interactions in the environment.
CIESIN hosts NASA's Socioeconomic Data and Applications Center (SEDAC) which offers freely available global populations or roads data sets (Link).
