The CIA World Factbook is a very useful starting point for retrieving simple and concise information about countries worldwide. Political, economic, demographic and geographical info of each country is classified by a complex metadata structure.
The World Factbook is prepared by the US Central Intelligence Agency. Information is provided by several national agencies as the National Science Foundation, the Bureau of Census, the Department of State
This website provides access to countries' profile, data and other integrated info, through its complex (but well-explained) metainfo and indicators structure
Almost all countries in the world are included in this publication, and many essential infos are also provided, though necessarily short and concise
This publication contains a lot of basic data on countries' political system, socioeconomic conditions, demographics, etc. - therefore quite relevant to PS, as for news on constitutionalization and democratization process, european integration, third-countries political developments
Since 2001, a system of frequent online updates throughout the year has been introduced