1902 Encyclopedia
Articles and illustrations from the Encyclopaedia Britannica, 9th Edition (1875) and 10th Edition (1902). Searchable by keyword and browsable by subject index.
Again, But Slower
Displays Wikipedia articles and their simpler counterparts side by side.
Encyclopedia Britannica
Provider of learning knowledge products through its online resources and distributed books and products.
Information Please
Knowledge resources featuring almanacs, atlases, encyclopedia, discitonary, thesaurus, and white pages.
Knol
User-written knowledge-base with comments sections for all articles.
Mashpedia
Offers a mashup of Wikipedia articles, Twitter tweets, and breaking news.
Qwiki
Encyclopedic guide featuring articles on various topics with several accompanying photos and maps.
Rudiments of Wisdom
Thousands of cartoons by Tim Hunkin, offering simple information in many different categories including biology, music, psychology, music, language, religion and engineering.
Scholarpedia
Features a peer-reviewed open-access encyclopedia, containing knowledge that is curated by communities of experts.
Visipedia
Visual encyclopedia project that is a collaboration between Caltech and UCSD.
Wikia
Offers a large assortment of topical wikis, as well as the traditional ability to edit them.
Wikipedia
Free open-source multilingual encyclopedia with volunteer editors.
World Book, Inc.
Official site promoting its excellence in the production of award-winning encyclopedias, reference sources, and multimedia projects for the home and schools.