(For some of these we do not have access to all content listed).
CIA World Factbook. Basic facts and history if you are just starting out.
Britannica Online. Same as above except more extensive. Useful for background but not a scholarly resource.
Cambridge Histories Online. Searchable text of the Cambridge Histories series. The regional history section has large multi-volume books on regions (e.g. Latin America and Africa) as well as large and populous countries (e.g. China and India).
Library of Congress Country Studies. Description and analysis of the historical setting and the social, economic, political, and national security systems and institutions of countries throughout the world.
Oxford Scholarship Online. Ebook portal with scholarly books on many topics including economic history. Good for overviews.
Economist Intelligence Unit (EIU) Country Reports and Profiles. Analysis of current economic and political events in more than 200 countries.
Human Development Report Library Includes the UNDP flagship publication the Human Development Report, as well as national human development reports from over 250 countries and regions.
Oxford Handbooks Online. Scholarly online historical encyclopedias and dictionaries.
World Development Report Library. Collection of the World Bank's flagship publication on economic development going back to 1978.