ICPSR maintains a data archive of more than 500,000 files of research in the social sciences. It hosts 16 specialized collections of data in education, aging, criminal justice, substance abuse, terrorism, and other fields.
Data from many survey research organizations; includes iPOLL, which provides access to individual questions asked on national public opinion surveys since 1935
The International Monetary Fund's (IMF) eLibrary simplifies analysis and research with direct access to the IMF’s periodicals, books, working papers and studies, and data and statistical tools.
Empirical data from the World Bank including its centerpiece dataset, World Development Indicators (WDI), with some data back to 1960 for up to 226 countries