AllWords.com - English dictionary with multi-lingual search capability.
Cambridge Dictionaries Online - Maintained by Cambridge University Press.
Dictionary.com - A mult-source dictionary search service produced by Dictionary.com.
Encarta World English Dictionary - English dictionary, thesaurus and translator.
Forthright's Phrontistery - Lists over 400 of the rarest modern English words.
Merriam-Websters Collegiate Dictionary - Maintained by Merriam-Webster, America's foremost publisher of language-related reference works
one hundred most mispronounced words - List of the most mangled words and phrases.
One Look Dictionaries - Search for words from a variety of online dictionaries.
Skeptics Dictionary - "A Critical Survey of Questionable Therapies, Eccentric Beliefs, Amusing Deceptions and Dangerous Delusions." 
WORDNICK - Detailed definitions, synonyms, audio pronunciation guides and usage data.
Your Dictionary - A web of on-line dictionaries, including language, subject specialties, translation, and many more.

ACRONYM

ALTERNATIVE

The Alternative Dictionaries -  Focuses on slang, profanities, and insults from all over the world. 162 dictionaries can be downloaded as PDFs. Select a dictionary and an alphabetized list of words appears. The heading of the selected dictionary gives the name of the language and the geographic region in which it is spoken. For example, the language Galician is spoken in Spain. The Galician word lacazan is slang for people who are lazy. It treats vulgar terms objectively with an eye to concision and reliability. Not all of the languages have entries.

botany

Ethnobotanical Dictionary (Tico) - Alphabetical listing by scientific name. Includes brief descriptions of usage and identifies cultures in which each plant is of interest.
Ohio State University Plant Dictionary - Plantfacts - An encyclopedia and hypermedia resource of information about plants with over 5,000 images and searchable databases.

computer/INTERNET

Computer Dictionary - On-line dictionary of computer terms.
COMPUTER DICTIONARY MAINTAINED BY SMART COMPUTING MAGAZINE -  Includes an encyclopedia with in-depth descriptions of terms.
Tech Encyclopedia - More than 14,000 definitions of computer terms and concepts.
Webopheia - Defines words, phrases, and acronyms related to computers and the internet.

FABLE

Age of Fable Or Beauties of Mythology - Written to "teach mythology not as a study but as a relaxation from study," these ageless volumes span the ages: from the Olympus of Zeus and the Valhalla of Thor, to the Round Table of King Arthur and the escapades of Robin Hood.
Dictionary of Phrase and Fable - Giving the Derivation, Source, or Origin of Common Phrases, Allusions, and Words That Have a Tale to Tell.

LATIN

Latin Dictionary. Translates English-Latin and Latin-English; allows searching by the stem of words; and includes a link to Words by William Whitaker, Latin to English with 39,000 entries. Maintained by the University of Notre Dame.

math

Dictionary of Units - A Dictionary of Units converts things like viscosity, spread rate, concentration, metrication, etc.
MATH - Outstanding math dictionary.

multi-lingual

Alpha Dictionary.com -  Directs users to the "best" multilingual dictionaries. Unique items include an English/Finnish dictionary, a Chinese characters Web dictionary, and the English/Danish Glossary of Electronics Terms
ECTACO Dictionary (multilingual) - Covers over 200 languages.
Multilingual Glossary Language Table - Multilingual glossary for library users.
yahoo Translations

MUSIC

Rap Dictionary - Latest definitions of hip-hop terminology.

physics

PHYSICS - Excellent resource for physics terms.

REVERSE

REVERSE DICTIONARY - Describe a concept and the site provides a list of words and phrases related to the concept.

SLANG

Infomime - virtual library of scholarly Internet resources relevant to faculty, students, and research staff at the university level maintained by the Library of the University of California, Riverside.
IN THE FIRST PERSON - English language personal narratives, including letters, diaries, memoirs, autobiographies, and oral histories. (Primary documents)
Librarians Index to the Internet for Washington State - Search the wealth of links on subjects, including Arts, History, Science and Philosophy, with a Washington State focus and sites selected in part by Washington State librarians and library employees.
National Geographic Society - Index to NGS publications (Find out when and where National Geographic covered a specific subject).

Specific Prize information:
    Chemistry
    Economics
    Literature
    Medicine
    Peace
    Physics

ABOUT BIG - Find the average income, cost of a car, diameter of the earth.  Travel through millions, billions, trillions, quadrillions, quintillions, and guacamoleons.
AGINGSTATS - The Federal Interagency Forum on Aging Related Statistics evaluates data collected by 15 major U.S. government agencies including the Administration on Aging and the Centers for Medicare and Medicaid Services.  It provides wide access to summarized data.
Adherents.com - collection of over 43,870 adherent statistics and religious geography citations: references to published membership/adherent statistics and congregation statistics for over 4,200 religions, churches, denominations, religious bodies, faith groups, tribes, cultures, movements, ultimate concerns, etc. The religions of the world are enumerated here.
American Factfinder - Searches for Census 2000 information by address.  Entering an address in the Advanced Geography Selection provides a pull down menu with choices of data, including census tract, block, and congressional district, as well as city, county, and state.
ASSOCIATION OF RELIGIOUS DATA ARCHIVES (ARDA) - Access to the best data on religion for educators, journalists, religious congregations, and researchers interested in American and international religions.  Data included in the ARDA are submitted by the foremost religion scholars and research centers in the world.
CENSUS OF AGRICULTURE - The census conducted by the U.S. Department of Agriculture provides consistent, uniform and detailed account of basic agricultural data.  There are quick links to specific commodities, as well as to state, county, and congressional district agricultural profiles.
COUNTY AND CITY DATA BOOK - Data for all top cities with a population of 25,000 or more.
County and City quick facts - Facts about people, business and geography.
FEDSTATS - Gateway to statistics gathered from more than 100 federal agencies.
GENDER STATISTICS - Aims to bring together both gender statistics and policies. Focus is on the production, dissemination and use of gender related data.  Maintained by United Nations Economic Commission for Europe (UNECE).
LABORSTA INTERNET - View and download labor data and meta data from over 200 countries and territories.  Maintained by the ILO Department of Statistics (International Labor Organization).
National Center for Educational Statistics - A rich source of data on a wide variety of topics.  Want to compare the U.S. to other countries?  Check the effect of education on voting?  This is the place. 
NationMaster.com - Large numerical database used as basis for interactively generating charts and maps.  Presents statistics from a variety of resources in an easy-to-use and interesting graphical format.
Population Reference Bureau - comprehensive virtual gateway to data and reports on population trends.   Provides timely and objective population information.
SalaryExpert.com - Provides salary data, broken down by job and geographic location, that is easy to use and authoritative.
State and Metropolitan Area Data Book --Comprehensive data for states and metropolitan areas.
STATE OF THE CITIES DATA SYSTEMS - Maintained by HUD's Office of Policy Development and Research.  Includes information on housing and economic development.  Access demographic and economic population characteristics, labor force data, job information, crime rates, etc.
Statistical Abstract of the United States
Statistical Resources - Site maintained by University of Michigan.
UNDATA - UN statistical databases  from which users can search and download a variety of statistical resources of the UN System.
United States Census Bureau
United States Government Statistics  - Site maintained by the University of Washington.
Washington State Census QUICK FACTS - Facts about the State of Washington.
Washington State Counties, Cities and Towns - Population counts that include age, sex, race, Hispanic origin, and household characteristics. (Note that this is a 617-page file in .PDF  format and will not work well on computer with slow connections).