The following list is meant to help you with your own research, by offering links to respectable information sources on the web, available free of charge. Inclusion on the list doesn't automatically mean the absolute truth is on these websites, so always be critical and compare information between different sources.
The content of the subsections is alphabetically organized.
Please add free online sources if you know some that are missing in this list, but try to keep it relevant and trustworthy.
FindArticles: Search results usually include free access to articles (esp sourced from British newspapers and magazines) not found through Google, including articles that pre-date widespread use of the Internet and even from the late 80s. Provided by LookSmart.
PubMedEntrez Global Query Cross-Database Search System. Free access to biomedical databases: online science textbooks, clinical trials, biomedical literature, Human genome, protein structure, taxonomy, etc. Put out by the National Library of Medicine.
American Enterprise Institute: private, nonpartisan, not-for-profit institution dedicated to research and education on issues of government, politics, economics, and social welfare.
Comparative Studies in Society and History: "Comparative Studies in Society and History" is an international forum for new research and interpretation concerning problems of recurrent patterning and change in human societies through time and the contemporary world."
OECD: Economic, social, and infrastructure data on industrialized countries.
The Overseas Young Chinese Forum (OYCF): "The Overseas Young Chinese Forum (OYCF) is established for overseas young Chinese to exchange their views on social, economic, political and cultural issues concerning China and to develop common aspirations through regular discussions."
Social Forces "Social Forces is a journal of social research highlighting sociological inquiry but also exploring realms shared with social psychology, anthropology, political science, history, and economics. The journal's intended academic readers include sociologists, social psychologists, criminologists, economists, political scientists, anthropologists, and students of urban studies, race/ethnic relations, and religious studies."
World Values Survey : "The World Values Survey is a worldwide investigation of sociocultural and political change. It has carried out representative national surveys of the basic values and beliefs of publics in more than 65 societies on all six inhabited continents, containing almost 80 percent of the world's population."
Review of Radical Political Economics: "The Review of Radical Political Economics (RRPE) publishes articles on radical political economic theory and applied analysis from a wide variety of theoretical traditions: Marxist, institutionalist, post Keynesian, and feminist. RRPE is published by Sage Publications."
Hoover Institution: "a public policy research center devoted to advanced study of politics, economics, and political economy—both domestic and foreign—as well as international affairs."
The Jamestown Foundation "The Jamestown Foundation's mission is to contribute to U.S. understanding of its strategic adversaries that pose a threat to democracy and freedom."
[1]: Kennan Institute for Advanced Russian Studies, Woodrow Wilson Center: think-tank on political, social, and economic issues affecting Russia and other successor states to the Soviet Union.
ALLBUS Data Service: online archive of German General Social Survey data. Free download - for scientific purposes - of high quality data on attitudes, behavior, and social structure in Germany.
Information and library science
Library, Information Science & Technology Abstract (LISTA): free article abstracts from "more than 600 periodicals, plus books, research reports and proceedings. Subject coverage includes librarianship, classification, cataloging, bibliometrics, online information retrieval, information management and more. Coverage in the database extends back as far as the mid-1960s."
Country Studies: Federal Research Division of the Library of Congress under the Country Studies/Area Handbook Program sponsored by the U.S. Department of Army (public domain text).
The LA84 Foundation Digital Archive: "Digital resources include academic journals, scholarly books, popular sports magazines of the late nineteenth and early twentieth centuries, and an extensive offering of Olympic publications. The Olympic titles include a complete run of back issues of Olympic Review, the official publication of the International Olympic Committee, and two dozen Olympic Games official reports."
Biographies
Dictionary of Canadian Biography Online: Biographies of people who have had an impact on Canada and who died between 1000 and 1920 or whose last known date of activity falls within these years.
Oxford Dictionary of National Biography: Resource for 55,000 biographies of people who shaped the history of the British Isles and beyond, from the earliest times to the year 2003. Login is required to access, and it's not strictly free - however, if you're in the UK, entering your library card number will almost certainly get you in. Many libraries elsewhere in the world also have unrestricted access.