U.S. State Department, Countries & Areas - overview with excellent historical and economic overviews, country leaders, politics, economy, and relations with the U.S.
CIA, World Factbook - starts with Afghanistan - select country for history, people and society, government, economy, energy, geography, communications, transportation, military, and transnational issues for 267 world entities
Country Profiles - history, politics and economic background of countries and territories, and background on key institutions; audio and video (BBC)
Brief profiles of most countries of the world, including government type and structure, names of major government officials, and an overview of foreign relations (by the U.S. State Department).
Search, read and compare constitutions from around the world. Developed by the authors of the Comparative Constitutions Project at the University of Texas at Austin.