Common Errors in English
DangerMom's Handy Dandy Grammar Guide
Dictionary.com
Hobbies: Writing
Seven Outdated Grammar Rules
So You Wanna Avoid Common Writing Errors?
Strunk and White's Elements of Style

Tips on Writing Fanfic

BTVS Writer's Guild Essays on Writing
Common Fanfic Errors
Dr. Merlin's Guide to Fan Fiction
Fanfic101
Fanfic Symposium
How to Write Almost Readable Fanfiction

Gilmore Girls Resources

Official Site
Gimore Girls.org
Gilmore Girls Episode Transcripts
Gilmore Girls at TV Tome
Quintessence (screencaps)

Writing Guides

Strunk & White: the classic writing guide. Snarky, brief, and informative.
Roget's Thesaurus: arranged both alphabetically and by topic for easy reference.
Harbrace Handbook: a bit dry, but it explains all those tricky grammatical constructs.
Woe Is I, Patricia O'Connor: It's like a grammar handbook for grammarphobes; breezy writing and lots of examples to explain common problems.
Eats, Shoots & Leaves: another well-written grammar guide, though this one is focused on the Queen's English, so some British-to-American translation is necessary.
Bird by Bird, Anne Lamott: Great insight into the frustrations and rewards of writing.

Please e-mail JeSouhaite if any of the links aren't working, or if you have suggestions for additional links.