Resources

The Elements of Style by William Strunk, Jr.
"...this classic reference book is a must-have for any student and conscientious writer. Intended for use in which the practice of composition is combined with the study of literature, it gives in brief space the principal requirements of plain English style and concentrates attention on the rules of usage and principles of composition most commonly violated."

Merriam-Webster Dictionary and Thesaurus Online
A source for definitions, pronunciations (via audio clips), synonyms, the "Word of the Day," and more.

Guide to Grammar and Writing
A wealth of information including grammar and punctuation rules and tips for writing better. Also has fun, interactive grammar quizzes to test your knowledge.

The OWL (Online Writing Lab) at Purdue University
A good resource for grammar, spelling, and punctuation rules. Also contains practice exercises for those who are serious about fine-tuning their grammar skills.

Good Grammar, Good Style
Numerous articles on English language usage. Topics include tips for writing effective e-mails, subject-verb agreement, and problematic pronouns.

American English
Traces the historical development of the various dialects of American English.

Etymologically Speaking
A listing of words that have interesting origins. A good page for those with an interest in etymology.

American Dialect Society's Word of the Year
Lists the words that are voted on as the most used (or perhaps overused) of each year.

References

hopefully

Merriam-Webster.com – hopefully

irregular verbs

Troyka, Lynn Quitman. Simon & Schuster Handbook for Writers, 6th ed. Upper Saddle River, N.J.: Prentice Hall, 2002.