The CIA (Central Intelligence Agency has compiled a website called The World Factbook. Information includes national government sites, embassies, statistics, statistics, etc.
The Constitute Project - This database offers constitutions, charters, amendments, and other related documents. Nations of the world are linked to their constitutional text posted on the Internet. Supported by the University of Richmond.
Organization of American States - The Organization of American States (OAS) brings together the countries of the Western Hemisphere to strengthen cooperation and advance common interests. It is the region’s premier forum for multilateral dialogue and concerted action.
The World Bank - The "World Bank" is the name that has come to be used for the International Bank for Reconstruction and Development (IBRD) and the International Development Association (IDA). Together these organizations provide low-interest loans, interest-free credit, and grants to developing countries.
Google InterGovernment Organization interface searches across hundreds of IGO websites, enabling users to research topics such as active IGOs working on HIV/AIDS in Uganda or other global issues.
The US Bureau of the Census sponsors the International Database which has a variety of demographic indicators for countries and areas of the world with a population of 5,000 or more.
The OECD has numerous databases on international topics. Their Education at a Glance database gives an overview of the state of education around the world.
The University of California Berkeley has a great site on Non Governmental Organizations (NGOs). NGOs are independent groups that work on public policy issues.