Writing
Purdue University On-Line Writing Lab (OWL)	Highly recommended.
University of Michigan On-Line Writing Lab	Clear; has good examples
CRAYON	Create Your Own Newspaper.
Technical Writing Textbook	By David McMurrey of Austin (TX) Community College

Grammar
Grammar Overviews	Presents grammar structures such as verb tenses, gerunds and infinitives, reported speech, the passive voice, the subjunctive, the verb wish, tell vs. say. By Mary Nell Sorensen of UW ESL.
Daily Grammar	Generously posted by veteran English teacher Bill Johanson from Canyon View Junior High, Daily Grammar provides simple and clear lessons on the basics of English grammar.
Guide to Grammar and Writing	By Charles Darling at Capitol Technical-Community College in Hartford, CT

Vocabulary
Weekly Word Watch	Probably best for advanced students.  From Cobuild, UK.
Practice your computer vocabulary	By Jim Schweizer in Japan.

Reading
Times.com	People, TIME, Fortune, Money, Entertainment Weekly, and lots more.
The Seattle Times	Local daily
The Seattle Weekly
The Washington Post Times	From Washington, D.C.
Bangkok Post	Newspaper from Thailand.
Study Aids for To Kill a Mockingbird	Used in our Reading for Pleasure class.

Activities
Homonym Quizzes - and quizzes on other topics	From Internet TESL Journal in Japan.
Interactive English Language Exercises	From International House, UK.

TOEFL
Computer-Based TOEFL	Official information from ETS, about the format and content of the new computer-based test.

Miscellaneous
Dave's ESL Cafe	Many activities, for example learning slang and idioms, finding an e-pal, and taking quizzes.
English Programs Around the World	ESL program websites