Subject Specific sites are to help you find ideas for teaching different content areas to students. Though most of your classes may just center around English, I have been to a few schools where students were also being taught by native speakers in Math, Science, Art, Critical Thinking, History, Writing, Literature, Business, Marketing, and Computers.  I've found some very unique sites about Financing, Game Theory, and Teaching Autism/Disabled Learners which may apply to your classes.  The links below will focus on specific subjects rather than make you search a broad teacher site to find what you are looking for.  Look for your desired subject to the right of the link. 
Register and receive financial lessons by e-mail
In depth info about States and Capitals in the USA
Math
Freedom of Speech - contributed by Steve Feld
Math TV Problem Solving Videos
English Grammar
Hundreds of Science Fair Projects with Instructions
American Press Institute
Journalism and Trainer Development
Space and Planet Science
Math
ArtiFAQs 2100 Time Portal
Art History - contributed by Steve Feld
Business English for Adults
Science
Breaking News English
 Complete ESL Lesson Plans for a variety of topics
Science
USA Atlas
Art
Drama and Theater
Learning America and the American Perspective
Language Education, Great Education Discussion Forum
Math and Critical Thinking - contributed by Steve Feld
English Learning Online
Mythology, Folklore, and Religion
Business English for Adults
English Structures
TOEFL, TOEIC, GMAT, MBA, EFL, ESL
English
ESL Lessons
Many Subjects Covered - Government Education Site
F.I.S.H.
 Funtional Skills Lesson Plans for Disability Learners Teachers
Science and Technology
For a small fee, Complete Downloadable Science Units
History, Development, and theories about Games
Math
Grammar and Writing
Guide to Learning English

English Resources for Students and Teachers

Writing
Math and Resources for Home Schooling Parents
Math Puzzles
ITESL
 ESL Learning in Spanish and English
James Rainville's ESL Page
Lots of Interesting Links and Resources
Covers All Subjects
King Tut Curse - Fact or Myth
Learning King Tut - contributed by Steve Feld
Learning Leonardo Da Vinci - contributed by Steve Feld
Lesson Plans for All Subjects
A Huge Online Linguistic Resource
Literacy Connections
 Reading and Literacy
Covers All Subjects
Articles, Tips, and Resources for Math and Literacy classes
Math
Math
Learning the Value of the US Dollar / Finance
Science and Technology
Science and Technology
Ideas for Developing Math Teachers
Science of Sir Isaac Newton - contributed by Steve Feld
Using TV Documentaries in Class
Everything Verbs
Creative Writing
Research Writing
Math, English, Reading
SAT Math Pro
Math Video Lessons
Science Experiments
Science
Special Needs and Autism Education
Speak Read Write
Student and Teacher English Resources
Social Studies
Lesson Plans for Many Subjects
Public Broadcasting Service Education Resources
Lesson Plans
History
Autism Resources
English
Top English Teaching
ELT Resources and Links
Free registration for Tons of English related Teacher Resources
Welcome to the Web
Teaching the Internet (Basics)