Encyclopedia

Britannica.com     -  "Featuring the Encyclopedia Britannica, the Web's best sites, and more."
Columbia Encyclopedia     -  6th edition. "The Columbia Encyclopedia began its existence in the 1920s when Clarke Fisher Ansley and Columbia University Press recognized the need for a “first aid” for those who read. Now in its sixth edition some 80 years later, The Columbia Encyclopedia continues to serve the purposes for which it was conceived. Containing nearly 51,000 entries (marshalling six and one-half million words on a vast range of topics), and with more than 80,000 hypertext cross-references, the current Sixth Edition is among the most complete and up-to-date encyclopediæ ever produced."
Encarta     -  MSN's online information site for learning and reference.
Encyclopedia Britannica Online     -  Subscription-based online access to the Encyclopedia Britannica.
Encyclopedia Smithsonian     -  "Encyclopedia Smithsonian features answers to frequently asked questions about the Smithsonian and links to Smithsonian resources on subjects from Art to Zoology."
Encyclopedia.com     -  "Encyclopedia.com was created by Infonautics Corporation to provide Internet users with a simple, one-stop research site. Composed of high-quality articles from the Columbia Encyclopedia, Sixth Edition, the site links more than 50,000 diverse articles to the resources available on Infonautics' popular online research service."
Fact Monster     -  For kids! Online almanac, dictionary, encyclopedia, and homework help.
Infoplease.com     -  "All the knowledge you need." Almanac, biographies, dictionary and encyclopedia.