Refdesk.com--loads of reference resources to use in your classroom--word of the day, today in history, in the news, random quotes, thought of the day, and lots of other facts
Infoplease.com--all the knowledge you need--almanacs, dictionary, encyclopedia, atlas, timelines, poetry, quizzes, etc. Excellent site to integrate into any content area
Dictionary.com--free online dictionary search, translator, word of the day, crossword puzzles, word games, language jokes, and vocabulary learning resources for many languages
Merriam-Webster.com--online dictionary and thesaurus--word games--word of the day--spelling bee hive
Encyclopedia.com--free online encyclopedia
Thesaurus.com--Searchable online version of Roget's Thesaurus of English words and phrases
Eduscapes--Online Reference Materials--excellent resources just waiting for you
The Internet Public Library (IPL)
The Teacher's Guide--Online Reference Tools--tons of links