US, UK, etc.

United States

DATA.GOV

The U.S. Government’s open data website with data, tools, and resources to conduct research, develop web and mobile applications, design data visualizations, and more.

FedStats
Access to statistical information from more than 100 U.S. federal agencies. Public access.

U.S. Census Bureau
The leading source of data about America’s people and economy. Public access.

Statistical Abstracts of the United States
Statistics on the social, political, and economic organization of the U.S., 1878 – 2012. Public access.

Bureau of Labor Statistics
Includes U.S. prices, employment and productivity statistics. Public access.

Historical Statistics of the United States
Summary of statistics on the social, political, and economic organization of the United States. Public access.

Pew Research Center
Statistics about issues, attitudes and trends shaping the United States. It contains public opinion polling, demographic research, media content analysis and other empirical social science research. Public access.

United Kingdom

Office for National Statistics
Statistics for UK economy, population and society at national and local level. Public access.

UK Census
Statistics from UK censuses 1801-2011. Public access.

Australia

Australian Bureau of Statistics
Social and economic statistics for Australia. Includes Census statistics. Public access.