About.com
http://about.com/
There are over 1.2 million pieces of original information, and more than 57,000 topics in this website. It offers advice and solutions for every day life and is searchable and browsable by categories.

Answers.com
http://www.answers.com/
This is a free online encyclopedia, which provides over three million entries with pronunciation and definition. It collects content from more than 60 titles from brand-name publishers, and it's own editorial team. Besides searching, it is also browsable in categories like business, health, travel, technology, science, entertainment, arts, history and so on.

Columbia Encyclopedia, sixth edition
http://www.bartleby.com/65/
Nearly 51,000 entries with more than 80,000 hypertext cross-references are searchable in this website. Other services such as dictionary, thesaurus, quotations, and English usage are also available.

Encarta
http://encarta.msn.com/
Encarta is an online encyclopedia available through Microsoft’s MSN service.  Its target readers are mainly high school and college students.

Encyclopedia Britannica Online
http://www.britannica.com/
Provides complete text of Encyclopaedia Britannica with search capabilities, related links, and multimedia enhancements. Free trial.

Fact Monster
http://www.factmonster.com/
Fact Monster, produced by InfoPlease is a children’s version of online almanac, dictionary, encyclopedia, and homework help.

HighBeam Encyclopedia
http://www.encyclopedia.com/
This is a free encyclopedia from Columbia Encyclopedia. Over 57,000 articles are searchable and browsable. Other services like publications search, multiple search engine, dictionary, and thesaurus are also provided.

How Stuffs Work
http://www.howstuffworks.com/
Articles explain how hundreds of things work, from elements of the human body to space-age technology.

Informationsphere.com
http://www.informationsphere.com/
Free online encyclopedia that allows users to submit their own articles for inclusion in its database.

Japanese Encyclopedia, by Private PDD library
http://www.cnet-ta.ne.jp/p/pddlib/japanese/index.htm
This encyclopedia is established by Private PDD library, which is regularly updated every 1 to 2 years. In Japanese (Hiragana).

Network Encyclopaedia, by Hitachi systems & services, Ltd.
http://ds.hbi.ne.jp/netencyhome/index.html
Provided by Hitachi systems & services, Ltd., a 3-minute free trial encyclopedia. Japanese definition is available in each entry. Subscribers can search without the 3 minutes limit between searches, whereas everybody else has to conduct searches every 3 minutes.

Symbols.com
http://symbols.com
The world's largest online encyclopedia of over 2500 graphic symbols

Wikipedia
http://en.wikipedia.org/wiki/Main_Page
Wikipedia is a project of Wikimedia Foundation, Inc., a not for profit organization promoting free access to full and multilingual information through wiki.  Wikipedia is a free online encyclopedia where readers are invited to edit the contents.  Wikipedia is available in 10 languages including English, French, German, Japanese, Italian and Polish.

Wordpedia
http://www.wordpedia.com/
A Chinese online encyclopedia compiled from various sources including Britannica, Chinese encyclopedia database, Taiwan abridged encyclopedia, Ylib dictionary, and more. Non-subscribers can read part of the content only; whereas subscribers can read the whole content.