Columbia Encyclopedia (Internet)
This is the sixth edition, 2000, of a well-known one-volume desk encyclopedia. This online version is searchable as well as browsable. Contains brief entries with keywords hyperlinked to related entries.

Wikipedia: The Free Encyclopedia (Internet)
"Wikipedia is a free content encyclopedia that is being written collaboratively by contributors from all around the world. The site is a WikiWiki, meaning that anyone ... can edit any article. ..." Without editorial oversight, the quality of the content on this site varies dramatically, but it is worth exploring. The English version has nearly 225,000 entries. Spanish, French, and Esperanto are among the several other languages offered.

The World Factbook (CIA)
Site offers in-depth information for individual countries, covering geography, people, government, and the economy, along with political and physical maps of the countries and of the world.

Oxford University Press -- Subject Specific:

adam Health Illustrated Encyclopedia (MedlinePlus)
The adam Health Illustrated Encyclopedia includes over 4,000 articles about diseases, tests, symptoms, injuries, and surgeries. It also contains an extensive library of medical photographs and illustrations.

Encyclopedia Mythica (Internet)
Mythology, folklore, mysticism, and more. Contains well over 4,000 definitions of gods and goddesses, supernatural beings and legendary creatures and monsters from all over the world. Some of the mythologies included are: Chinese, Etruscan, Greek, Latvian, Native American, Norse, Persian, and Roman.

Internet Encyclopedia of Philosophy (Internet)
A searchable database of basic philosophy information and definitions. Visitors to the site can search by keyword, click on a letter to browse subjects in the collection, or read a small library of philosophy texts in HTML format.

International Encyclopedia of Sexuality (Internet)
Three-volume encyclopedia summarizes the sexual attitudes and behavior patterns of thirty-two countries. Written by 170 sexologists in the respective countries and cultures, each entry explores such areas as heterosexual relationships, children, adolescents, adults, gender-conflicted persons, unconventional sexual patterns, contraceptions, sexually transmitted diseases, AIDS, sexual dysfunctions, and therapies. It also includes sexual issues for older persons and physically and mentally challenged individuals

Stanford Encyclopedia of Philosophy (Internet)
Philosophy professors at Stanford University are developing this encyclopedia, which is designed so that the authors of articles can update them as needed. Twelve editors and 120 scholars thus far have contributed to the encyclopedia, and the project's leader expects to have most entries completed within five years. Of almost 500 entries listed on the contents page, more than 80 have been completed and nearly 100 others have been assigned as of December, 1998.