Britannica.com.
Formerly a fee-based encyclopedia, searches are now free and include articles from over 70 leading magazines and the washingtonpost.com.

Catholic Encyclopedia.
More than 11,000 articles on Catholic topics. Search by keyword or alphabetically.

Concise Encyclopedia of Economics.
From The Library of Economics and Liberty a concise encyclopedia of economics, including biographies.

Encyclopedia.com.
Has over 57,000, frequently updated articles, from the Columbia Encyclopedia. Each article is enhanced with links to newspaper and magazine articles as well as pictures and maps from eLibrary.

Encyclopedia Mythica.
Covers cultural mythologies, folklore, legends, and more.

Encyclopedia of Earth.
An electronic reference about the Earth, its natural environments, and their interaction with society. The Encyclopedia is a free, fully searchable collection of articles written by scholars, professionals, educators, and experts who collaborate and review each other's work. The articles are written in non-technical language and will be useful to students, educators, scholars, professionals, as well as to the general public.

Encyclopedia of Psychology.
This site is intended to facilitate browsing in any area of psychology. It includes original information and a hierarchical database of links to websites providing information about scientific psychology.

Encyclopedia Smithsonian.
Has links to resources on subjects from Art to Zoology.

Encyclopedia of Television.
From the Museum of Broadcast Communications, this site includes histories of major television networks, broadcasting systems around the world, people, policy disputes and entertainment trends.

Encyclopedia Virginia.
A chronicle of the state’s history, politics, and geography through the perspectives of all the ethnically, culturally, and linguistically diverse peoples that have lived there.

Holocaust Encyclopedia.
From the United States Holocaust Memorial Museum, browse articles or search by keyword for articles about the Third Reich, rescue and resistance, victims, and post-holocaust information.

Stanford Encyclopedia of Philosophy.
All entries are refereed before they are made public. Search by keyword or alphabetically.

Symbols.com.
Online encyclopedia of Western signs and ideograms.

Wikimedia Commons.
A central repository for freely licensed photographs, diagrams, animations, music, spoken text, video clips, and media of all sorts. A useful database but, be aware of their disclaimer: "Wikimedia Commons is not uniformly peer reviewed; while readers may correct errors or remove erroneous suggestions they have no legal duty to do so and thus all information seen here is without any implied warranty of fitness for any purpose or use whatsoever."