11 Rules of Writing - This site is a concise guide to some of the most commonly violated rules of writing.
100 Words That All High School Graduates And Their Parents Should Know - The quality of a person's vocabulary has a direct effect on his or her success in college and in the workplace. In response to parents' misgivings over the quality of their children's education, the editors of The American Heritage College Dictionary have compiled a list of 100 words they recommend each high school graduate should know.
American Heritage Book of English Usage - A powerful, practical and authoritative guide to contemporary English usage that will help you make intelligent decisions when communicating in speech or writing. Site presents sound guidelines and specific controversies in grammar, style, and word choice.
Antagonyms - words that have opposite meanings (e.g., "bad" can mean bad or good depending on usage).
AskOxford.com - Free English language reference site from Oxford University Press. The site has a range of resources including dictionaries, a thesaurus, word games and writing guides as well as the opportunity to put any language related question not answered by the site to OUP's resident language experts.
Common Errors in English - site which simply and entertainingly explains a number of common spelling and usage errors in English.
Commonly Confused Words - An alphabetical listing of frequently used and sometimes misused words, with explanations and examples of proper usage.
Confusing Words - Confusing Words is a collection of 3210 words that are troublesome to readers and writers. Words are grouped according to the way they are most often confused or misused. Some of these words are homonyms (words that sound alike but are spelled differently) and some are just commonly confused.
Correct Forms of Address - This section provides the correct forms of address for U.S. Public officials, diplomats, religious leaders, royalty, the British peerage, and military personnel.
Daily Grammar - improve your writing with free daily e-mail grammar lessons.
Darling's Guide to Grammar - prepared by Professor of English/Humanities Charles Darling for his English courses at Capital Community-Technical College.
Garbl's Writing Center - This style guide gives writing and editing advice about abbreviations, capitalization, English grammar, numbers, organization terminology, punctuation, spelling, word usage and the World Wide Web.
Grammar Bytes - explanations, handouts for students and teachers, and interactive exercises.
GrammarCheck.net - "Now you can grammar and spell check any text or document online. Simply copy and paste your text onto our website to proofread, review, and correct it."
Grammar Now - "This is a free site dedicated to answering any grammar, composition, research or formatting question you might have. Send me a grammar question by filling out the form below, and I'll e-mail you a response."
Grammars and Language Courses - This site by yourDictionary.com provides links to online grammars and language courses along with links to lesson plans and other resources for learning the languages.
Grammar Slammer Online - online English grammar help. Includes letter writing, confusing words, and easy search engine.
Handbook of Rhetorical Devices - definitions and examples of more than sixty traditional rhetorical devices, all of which can still be useful today to improve the effectiveness, clarity, and enjoyment of your writing.
Heteronyms - words that are spelled identically but have different meanings when pronounced differently (e.g., wind or lead).
Indispensable Writing Resources - You'll find everything on and off the Net that you could possibly need in writing or researching a paper, including links to all sorts of reference material, links to writing labs, links to Web search engines, and links to writing-related Web sites.
Jargon Buster - If you're confused by conjugation and puzzled by the postpositive then this service by Oxford Dictionaries called 'jargon buster' should help you cut through the technical terms and grab hold of grammar, literary terms, and other such bamboozlement.
King's English - HW Fowler's classic reference guide to vocabulary, syntax, punctuation, grammar, and style.
Paradigm Online Writing Assistant - site offers a guide to writing essays and term papers. Modules include choosing a topic, organizing your writing, editing your writing, documenting your research, and writing various kinds of papers: informal, thesis, exploratory, argumentative.
Phrase Finder - Whether you want to resolve a friendly argument over how a saying or phrase originated or whether you just enjoy words, you'll probably find something here to interest you.
Word Police - "The Word Police are looking for a few good people. As a certified Word Police officer, you will be entitled to issue Grammar Citations when you see or hear crimes against the language. To be inducted into the force, you must pass a Word Police Academy exam."
The World's Famous Orations, William Jennings Bryan, Editor-in-Chief - Two millennia of Western Civilization come into focus through these 281 masterpieces by 213 rhetoricians. Selected under the supervision of the greatest orator of his time, these brief persuasive addresses form both a window into history's turning points as well as a timeless collection for any reference shelf.
World Wide Words - Michael Quinion's language pages include articles, the word hoard, newsworthy words, and usage notes.