Big Dog's Grammar - A fun and easy-to-follow guide to the basic rules of English grammar. (Personal site, by Scott Foll)
Dr. Goodword's Word Wizard
- Colorful vocabulary website designed for kids aged 7 - 13, featuring games, puzzles, and other fun learning activities. (Commercial site: Lexiteria LLC)
Grammar Bytes - Definitions of common grammar terms, fun quizzes, quick tips and rules. (Personal site by Robin L. Simmons, Valencia Community College)
Interesting Things for ESL Students 
- Word games, puzzles, quizzes, slang, proverbs and more, for students of English as a second language (personal site by Charles I. Kelly & Lawrence E. Kelly, Aichi Institute of Technology, Japan). For more English/ESL links, see South Plainfield Public Library's Useful Websites: LANGUAGE page.
Vocabulary University - Word puzzles and other exercises to help build your English vocabulary. Divided into three grade levels. (Commercial site, by Jan Cook and Carey Orr Cook)
Dr. Grammar - This website provides answers many commonly-asked questions about English grammar (lay or lie? good or well? its or it's?) and also offers resources on grammar, word origins, English as a Second Language, citing sources, and more. (University of Northern Iowa)
Sentence Sense - An online textbook in basic writing, examining how sentences work, reviewing errors that commonly appear in written English, and suggesting techniques and topics for developing ideas in writing. (Capital Community College, Hartford CT)
Visuwords™ - This online graphical dictionary can help you understand how words are related. When you look up a word, Visuwords will produce a diagram which graphically illustrates that word's associations with other words and concepts. Be sure to read the brief instructions at the bottom to get the full benefit of the site. (Commercial site)
Vocabulary Games 
- Fun quizzes to help you learn SAT / GRE words, improve your vocabulary context skills, and learn computer or medical terminology. (Commercial site: Sheppard Software)
Literacy Rules: Language Arts Help - Scroll down to 'Useful Information' for a list of handy printable PDF fact sheets on various language-related subjects, including 'Punctuating Conversation', 'Commonly Misspelled Words', 'Basic Essay Answer', 'Poetry Terms', 'Grammar Quizzes', and more. For middle school students and teachers. (Personal site by Consuella Jackson)
Guide to Grammar and Writing - This site on English grammar defines the different parts of speech (nouns, adjectives, etc.), explains sentence structure, and provides tips for composing good sentences, paragraphs, essays, and research papers. Also offers quizzes, FAQs, and other helpful tools. (Capital Community College Foundation, CT)
Ask Oxford - An authoritative source of guidance for those wishing to write or speak English correctly. The site includes English FAQs, dictionaries, quizzes, crosswords, quotes, language links, and more. For American English, choose 'US view' near the upper right-hand corner of the page. (Oxford University Press)
Commonly Confused Words - Lists dozens of commonly confused word pairs, such as affect & effect, discreet & discrete, and flaunt & flout, with tips on how to use them correctly (Oxford University Press).
Dictionaries: Farlex Free Dictionary - 'English, Medical, Legal, Financial, and Computer Dictionaries, Thesaurus, Acronyms, Idioms Encyclopedia, a Literature Reference Library, and a Search Engine all in one.' Merriam-Webster Online offers an online dictionary, thesaurus, Spanish - English dictionary, plus word games, puzzles, podcasts and other features. Merriam Webster also hosts Word Central for younger students, with games, daily buzzword, and 'Build Your Own Dictionary' feature. Your Dictionary includes a dictionary, thesaurus, grammar, and more, plus a directory of Specialty Dictionaries covering many subjects in business, arts, sciences, education, trades, sports and hobbies. All the above dictionaries provide pronunciation audio. Use the OneLook® Dictionary Search to search dozens of web-based dictionaries from one site. (All commercial sites)
Diagramming Sentences - Diagramming sentences is a way to visualize how the different parts of a sentence fit together. On this page, you can learn the process one step at a time, or jump to a particular section using the table of contents. (By Dr. Kip Wheeler, an English professor at Carson-Newman College)
Elements of Style - William Strunk's classic reference book on 'the principal requirements of plain English style... the rules of usage and principles of composition most commonly violated. (Bartleby.com; commercial site)
Grammar Hotline Directory - Can't find the answer to your English grammar questions online? This site offers a listing of colleges and universities which will answer short grammar questions by telephone or e-mail. (Tidewater Community College, VA)
How to Write a Paper and Cite Sources - Selected links to sites offering guidance on planning, researching, and writing an essay or term paper. (South Plainfield Public Library)
New Words and Senses - A sampling of new words and new definitions of words that were added to the Merriam-Webster's Collegiate® Dictionary in 2006, such as 'mouse potato', 'biodiesel', and 'supersize'. There is also a page with 20 of the new words for 2007 and 2009 (Commercial site)
Picture Dictionary - Look up a noun by first letter or category to see a simple picture of that object. You can look up words in English, French, German, Italian, or Spanish. Merriam-Webster offers a more extensive Visual Dictionary Online , which includes detailed, labelled images and audio pronunciation. A similar site is Visual Dictionary, which offers images labelled in English or French. (Commercial sites)
Proofreading Symbols - Meanings and examples of common proofreading symbols and abbreviations, with links to some online aids for proofreading and editing. (Capital Community College)
Word of the Day [UPDATED LINK!] - Increase your vocabulary by learning a new word each day; site provides both definitions and usage examples. THIS SITE DOES NOT WORK IN INTERNET EXPLORER 6. (Commercial site: New York Times / Merriam-Webster)
Wordsmyth - A simple, easy-to-use online English dictionary and thesaurus.
Writing Resource Center - Online resources to help you learn about academic writing & research, business writing, grammar & punctuation, spelling & mechanics, and more (Empire State College). Links to additional writing resources, arranged by subject, are available from the University of Kansas Writing Center [UPDATED LINK!].
Collections of websites for Language Arts Educators:
http://school.discovery.com/schrockguide/arts/artlit.html
http://melvil.chicousd.org/engl.html
http://www.acs.ucalgary.ca/~dkbrown/index.html
http://school.discovery.com/schrockguide/arts/artlit.html
http://teachers.henrico.k12.va.us/Specialist/franceslively/resources/novels_ms.html
Plot Line:
http://blogs.canby.k12.or.us/uploads/wiesehas/bpms%201/Short%20Stories/plot%20line.jpg
Collections of Websites for Language Arts: