In addition to library resources, lots of economic data, domestic and international, is freely available online. This page contains links to just a few potential sources.
The Census Bureau's data access point, including current data (back to 2010) from the decennial census, the American Community Survey, the Economic Census, and more.
"Explore the most complete set of 6.6 million time series covering more than 200 economies, 20 industries and 18 macroeconomic sectors - compiled from 2,200 sources worldwide."
Called the "social network for data people," this relatively new site lets you sign up and share datasets with other researchers, or download datasets that may have been manipulated or changed to be just what you need for your own research.
Historical time series data for the U.S. economy which includes daily U.S. interest rates, CPI, PPI, GDP, monetary data, exchange rates, balance of payments and more. Data may be exported into Excel or text files.
The same data as is available through FRED, the Federal Reserve Economic Data portal, but this page provides it nicely mapped in various geographies -- county, state, or international.
This semi-annual report from the IMF's International Capital Markets Department reports on market developments and issues. The Statistical Appendix especially includes GDP figures, capital flows (direct investment, etc.), data on the securities markets, and much more.
The International Monetary Fund's IFS database contains data on exchange rates, commodity prices, consumer prices, interest rates, and other economic indicators.
The online library of the Organisation for Economic Co-operation and Development (OECD) featuring its books, papers and statistics and is the gateway to analysis and data.
IBISWorld has excellent, detailed industry surveys for virtually any industry. View the tabs across the top for details on the state of the industry. View the farthest-right tab, Key Ratios, for key numbers.