There are a wide variety of data sources out there with data relevant to institutional and economic development.
World Bank – cross-country data on over 1,000 different indicators
Penn World Tables –
comprehensive data from national accounts for 1950 – current.
Organization for Economic Development – Statistics –
Comprehensive data on the developed countries, also has extensive data on developing countries. In particular, a good source of data on foreign aid and international trade/FDI flows.
Centre for the Study of Civil War –
Websource for the Uppsala Conflict Data Program. Very good data on war and conflict.
DEVECONDATA is a blog for
information about datasets relevant to development economists.
Economic Growth Resources is a website that contains links to resources relevant to the field of Economic Growth. It was last updated in September, 2006 so some of the information may be out of date.
In my research I make considerable use of data that is available in GIS form. Two good sources of GIS data are the Atlas of the Biosphere and the GeoData Portal at the UNEP. The UNEP site also contains considerable information available in a non-GIS form, though much of it is also available through the World Bank site linked above.