International in scope. Lists 2000 data repositories worldwide. You may browse and search by subject. Has detailed information on the repositories as well as links.
Contains information on databases and repositories in Scientific fields - with an emphasis on biology and life sciences. Deep indexing allows the user to even search by biological taxonomies.
Primarily a behavioral, health and social science repository. ICPSR is subscription based and therefore not all data deposited is open to everyone. OpenICPSR contains specific subject repositories.
One of a number of Dataverse (open source data repository) communities around the world, the Harvard-based repository will accept data deposits from throughout the United States.