Gale Virtual Reference Library is an online reference collection containing over 400 full text encyclopedias, handbooks, and specialized reference books. It's a good resource to consult when you want to learn about a topic, a literary work, or find factual information. You can search the whole collection, search under specific subject/ topic, or browse a book full-text online.
Opposing Viewpoints in Context provides access to full text literature about many current controversial issues, including affirmative action, globalization... Each topic includes viewpoint essays, topic overviews, newspaper and magazine articles, statistics, and links to related web sites.
CQ Researcher is another good database to use when learning/ writing about current social, political, and economic issues. Each report includes a concise overview of an issue, historical background, opposing arguments, statistics and polls, and suggestions for further reading.
Academic Search Complete is a large multidisciplinary database containing scholarly and popular publications in a wide variety of subject disciplines. A good starting point for almost any topic you are writing about.