Online Reference Desks

Refdesk.com is self-entitled "the single best source for facts on the web"--contains basic reference shelf resources.

Digital Librarian: A Librarian's Choice of the Best of the Web  offers hundreds of links to every subject imaginable—truly some of the best sites available to students, too.

LibrarySpot has a huge assortment of reference resources--all in one place; links to  encyclopedias, special library collections, almanacs, biographies, and every other type of reference material are available here.

Online Encyclopedias

Encyclopedia.com is the online site for the Concise Columbia Electronic Encyclopedia, Third Edition. 

Columbia Encyclopedia has over 50,,000 articles entries plus a search feature to fiction, non-fiction, and verse articles.
 

Online Dictionaries/Thesauri

Merriam-Webster Online: the Language Center is based on the print versions of Merriam-Webster's Collegiate (R) Dictionary and Thesaurus.

Dictionary.com has a searchable English dictionary plus dictionaries in German, Greek, Latin, Spanish, etc.

Biographical Dictionary contains more than 28,000 notable men and women from ancient times to the present day; the biographies are brief.

Thesaurus.com provides users with a searchable thesaurus plus a search for antonyms, crossword and word search puzzles, and writing resources; this site also has a fun translator that translates English to Spanish, French, Portuguese, German, etc.