Dictionaries & Thesauruses
dictionary.com: Find the definition for just about any word.
Merriam-Webster Online Dictionary & Thesaurus: Free dictionary & thesaurus from Merriam-Webster
thefreedictionary.com: English, Medical, Legal, and Computer Dictionaries, Thesaurus, Encyclopedia, a Literature Reference Library, and a Search Engine

Encyclopedias
academickids.com: an online encyclopedia with thousands of free articles.
encyclopedia.com: Search over 200 individual encyclopedias and reference books from the worlds most trusted publishers.
Encyclopedia Britannica Online: Search for information.
Wikipedia: a free-content encyclopedia in many languages.

Measurements & Conversions
calculator.com: Online calculators to help you solve problems and do unit conversions.
convert-me.com: Online calculators for quick and easy metric conversion, conversion tables for both commonly used and very exotic units.
factmonster.com - Measurement: Tables to help you convert from 1 measurement to another.
onlineconversion.com: Convert just about any measurement to another measurement.
processassociates.com: General conversion factors calculator for all kinds of measurements.
sizes.com: Index of thousands of world measurements.

Questions & Answers
ask.com: Get answers to your homework questions or any question.
askmehelpdesk.com: Online expert community where you can ask questions in hundreds of topics and have them answered for free by experts.
itools.com: Search, language, research, financial, map, and more tools.
jiskha.com: Jiskha Homework Help
mit.edu - START: Web-based question answering system from MIT can answer millions of English questions about places (e.g., cities, countries, lakes, coordinates, weather, maps, demographics, political and economic systems), movies (e.g., titles, actors, directors), people (e.g., birth dates, biographies), dictionary definitions, and much, much more.

Article Search
findarticles.com: The web's first free article search.
Google Scholar: Search provides a simple way to broadly search for scholarly literature. Search across a wide variety of disciplines and sources.jstor.org: Search journals, primary sources, and books on JSTOR.

Newspapers & Magazines
abyznewslinks.com: Access newspapers and news sources from around the world.
Elephind.com: Search all of the world’s free digital newspapers from one place and at one time. A work in progress.
Library Of Congress: Search U.S. Newspaper Directory, 1690-Present.
USA Newspapers: ( Internet Public Library): Resource to find links to online newspapers by state in the US. Includes sources for periodicals from throughout the world.
Magatopia: Free online magazine directory.

Language Translations
Google Translate: Google's free service instantly translates words, phrases, and web pages between English and over 100 other languages.

Other References
Atlapedia Online: Full color physical maps, political maps as well as key facts and statistics on countries of the world.
CIA: The World Factbook: Find up to date information about any country.
csulb.libguides.com: Free Databases (all subjects): Encyclopedias.
Homework Help - 1 America: Links to reference tools, writing tools, history, geography, science, math, etc.
Infoplease Homework Center: Includes encyclopedia, dictionary, almanacs, and homework help on English, math, history, geography, science, and social studies.
kidsclick.org: Billed as a search site for kids, but it covers topics of interest for all ages, from kindergartners to seniors. It offers links to a broad range of homework topics, from algebra to zoology.
refdesk.com: Excellent source for facts and information about many different topics.
referencedesk.org: Gateway to many online reference sites including dictionaries, encyclopedias, thesauri, facts of the day, and more.
Smithsonian: Resources from the Smithsonian Institute.
The Virtual Reference Desk - virtualref.com: Provides help to academic researchers on a variety of topics