Association of Religion Data Archives (ARDA)
http://www.thearda.com/
The ARDA contains many datasets pertaining to religion, including both surveys on religious attitudes and data on denominations and denomination membership. Denominations data are available down to the county level roughly every decade, back to 1890.
Center for Population Economics (CPE)
http://www.cpe.uchicago.edu/
The Center for Population Economics at the Booth School at the University of Chicago provides various health-themed data, such as collections that combine pension data, medical examinations, and Census records for Union Army veterans and Colored Troops Infantry veterans, and urban public health data for select cities in the late 1800's and early 1900's.
Data and Information Services Center (DISC) at the University of Wisconsin-Madison
http://www.disc.wisc.edu/
DISC has a very eclectic archive that includes data on topics such as property surveys for Verona in 15th-century Italy, race riots in the United States between 1961 and 1968, and Mexican political elites. Various datasets in the archive are also accessible via U-Wisconsin's BADGIR interface.
Economic History Services Databases
http://eh.net/databases/
Economic History Services, which is supported by the Economic History Association, is a collection of resources for scholars of economic history. Among its various resources is a collection of databases, covering topics such as Confederate Greyback prices. The site also provides links to related data resources hosted elsewhere.
Historical Census Browser
http://mapserver.lib.virginia.edu/
The Geostat Center at the University of Virgina has compiled county-level data from the U.S. Census from 1790 to 1960 (using data from ICPSR #0003) and made that data available via a very-user friendly web brower.
Human Mortality Database
http://www.mortality.org/
UC-Berkeley's Human Mortality Database contains vital statistics measures for various countries, covering most of the 1900's and onwards. Time coverage varies by country. Geographic coverage primarily focuses on Europe but also covers select countries in Asia and the Americas. Related data are available for a broader range of countries with the Human Life-Table Database from the Max Planck Institute for Demographic Research.
IPUMS (Integrated Public Use Microdata Series)
http://www.ipums.org/
The IPUMS project at the University of Minnesota has compiled samples of microdata from the Census of Population and Housing for 1850-2000 and the American Community Survey. The IPUMS projects and collections include more specialized resources such as samples from the 1850 and 1860 Censuses of Slave Inhabitants and the North Atlantic Population Project. These microdata files are generally very large and are designed for usage with statistical software such as SAS, SPSS, or Stata.
IPUMS International
https://international.ipums.org/international/
IPUMS International is another University of Minnesota project, this time devoted to standardizing and distributing microdata from population censuses in various developing and developed countries. These microdata files are generally very large and are designed for usage with statistical software such as SAS, SPSS, or Stata.
League of Nations Statistical Yearbooks
http://digital.library.northwestern.edu/league/stat.html
Statistical yearbooks from the League of Nations are available as .pdf files from Northwestern University.
Medieval and Early Modern Data Bank (MEMDB)
http://www2.scc.rutgers.edu/memdb/index.html
The MEMDB project at Rutgers University provides access to various collections of economic data for the medieval and early modern periods of European history.
National Bureau of Economic Research (NBER)
http://www.nber.org/data/
In addition to its work on business cycles, the NBER has an eclectic data archive that covers topics such as international shipments of gold during the Gold Standard, medical data on veterans of the Union Army, and U.S. vital statistics reports from 1900-1968.
National Historical Geographic Information System (NHGIS)
http://www.nhgis.org/
The NHGIS project at the University of Minnesota provides aggregated historical Census data on population, economics and agriculture at different levels of geography (state, county, or tract, depending on the Census year and category of information). For those experienced with using GIS software, the NHGIS project also distributes historical boundary files for Census tracts.
Roper Center for Public Opinion Research
http://www.ropercenter.uconn.edu/
The Roper Center is one of the country's premier centers for polling data, with public-opinion data for the United States extending back to 1935. The iPOLL interface may be of particular use because it allows users to search through surveys at the question level. While Roper's holdings focus mainly on the United States, its archives also include much data from other countries, such as this 1963 USIA survey of residents of West Germany or this collection of surveys from Latin American countries. This resource is also available via Databases at Emory.
Social Explorer
http://www.socialexplorer.com/
Social Explorer provides quick and easy access to current and historical census data and demographic information. Its contents include the entire U.S. Census from 1790 to 2010, annual updates from the American Community Survey, data on religious congregations for the United States for 2009, decennial religious congregation data for 1980-2010, and carbon emissions data for 2002. Users can create reports and maps at various levels of geography, including counties, Census tracts, Census block groups, and zip codes, depending on data availability. Social Explorer is also available via Databases at Emory.
World-Historical Dataverse
http://www.dataverse.pitt.edu/index.php/
The World-Historical Dataverse "is the University of Pittsburgh affiliate of a wider project to address the need for comprehensive historical data on the human experience at the global level. This project is intended to the contribute to creation of a comprehensive set of data on social-scientific, health, and environmental data for the world as a whole and for its constituent regions and localities, for the past four or five centuries," to quote the project. It hosts its own collection of datasets as well as other individual datasets on particular topics. The project also provides links to external data portals and external datasets