Inter-university Consortium for Political and Social Research (ICPSR), Michigan USA
The ICPSR Data Archive offers a collection of datasets and abstract on Historical and Contemporary Economic Processes and Indicators (downloadable, but access is restricted to authorised users)

National Bureau of Economic Research, USA
U.S. historical macroeconomic series (downloadable), and Savings and Investment in 13 countries, 1850-1945 (downloadable)

Scottish Economic History Database, 1550 - 1780
Data collected during a project on Scottish wages and prices (online database)

Groningen Growth and Development Centre
A research group of economists and economic historians at the Economics Department of the University of Groningen. The group carries out research on comparative analysis of levels of economic performance and differences in growth rates in the world economy