Encyclopedias, Dictionaries, Almanacs, Atlases

Encyclopedias

Columbia  -  quick answers to many questions
Encyclopedia.com - credible, reliable information from published sources
Information Please - Encyclopedia and dictionary

Dictionaries, Thesauruses, and Translators

Babel Fish Translator - translates boxes of text or full web pages

Reverse Dictionary - use this site to look up a word by its definition
Google Language Tools - translates text and/or web pages in a variety of languages

Howjsay - An online talking dictionary of English pronunciation
Information Please Dictionary
Law Dictionary - defines legal terms defines legal terms
Medical Dictionary - defines hundreds of medical terms
Merriam-Webster Language Center - offers a dictionary and a thesaurus

OneLook
Picture Dictionary - designed for language learners of all ages
Rhyme Zone - a rhyming dictionary and thesaurus
YourDictionary.com - offers content from more than 2500 dictionaries in more than 300 languages              
Webopedia - defines computer and Internet technology definitions
Webster's Word Central - features links to related words and a rhyming dictionary

Almanacs

CIA World Factbook - provides detailed information for 266 world entities
Fact Monster - a fun almanac designed for middle school students
Information Please Almanac - authoritative answers to all kinds of factual questions
U.S. Census Bureau - provides, business, people, and geography information about the U.S.
World Almanac for Kids - connect to facts about animals, nations and states, sports, and more
                      

Atlases and Maps

Atlapedia Online - full color physical maps, political maps as well as key facts and statistics on countries of the world
American Memory Map Collections: 1500-2003 - The Library of Congress collection of historical maps
Historical Map Collection, University of Texas - hundreds of maps arranged by region
Maps on U.S. - "navigation made simple"
Mapquest - type in an address and get a map
National Atlas - U.S. Atlas offering multimedia maps, and users can create their own detailed maps
National Geographic's Map Machine - offers a full World Atlas and more
Places in the News - maps of areas in the news today
World Atlas.com - graphic maps of the continents and countries