TwisterJester

Writers' Resources

Dictionaries, Encyclopedias, and General References:

Miriam Webster

Webster isn't the most comprehensive site, but it does offer an online dictionary AND online thesaurus.

Bartleby.com Resources

Besides offering books for sale, Bartleby offers a wonderful array of writers' tools and references. If you want to clean up grammar, this site carries several guidebooks, all for free.

Dictionary.com

English Grammar, Spelling, and Punctuation:

11 Rules of Writing

Guide to Grammar and Writing

Creative Writing for Teens (Good basic instructions for adults, too!)

SpellCheck.net

The Blue Book of Grammar and Punctuation

The Spelling Doctor

Block Busters:

These are for those writer's block moments when you need a few minutes of something completely mindless. You can go here and come back to writing without losing much in the process.

Atomica

Special Resources:

Rhyme Zone

The Phrase Finder

International Money Exchange Rates

Instant Translator

Authors' Agents:

Literary Agents: What to watch for!

Authorlink: Alphabetical Listing of Agents

Literary Agents Guide

Predators and Editors

Directory of Publishers

WritersNet

Search Engines

Google

There are other search engines (lots of them, in fact) but none as comprehensive as GOOGLE. If it's on the web, it's on Google. Period.