With over 460 up-to-date articles on all sorts of ELT related subjects the ICALwiki is a great free ELT resource for all English teachers and other TESL/TEFL Professionals.

The ICALwiki offers practical ideas and insightful suggestions on a wide array of teaching related topics from Grammar to ESL Activities to Books to Linguistics to Teaching Faq to Country Files and much, much more. Check it out!