About.com: English as 2nd language http://esl.about.com/od/englishgrammar/English_Grammar_Help_Rules_Worksheets_Games_Quizzes_Exercises.htm
A comprehensive compilation of rules, worksheets, handouts, games and lesson plans as well as explanations of essential grammar rules.
Azar Grammar.Com: Teachers helping Teachers
This companion website to the Azar Grammar Series offers a range of materials to aid teachers whether or not they are using the series. The full text of Fun with Grammar is offered as a free download.
Offering almost 5,000 grammar worksheets, Busy Teacher also presents articles on how to teach grammar. The section on grammar is divided into clearly labeled categories.
A collection of a variety of short articles written by ESL/EFL teachers from different nationalities and countries.
ESL Fun Games
Games are listed at three learning levels as well as grouped by subject. They include classics such as “Wheel of Fortune” and “Snakes and Ladders.”
Grammar Girl – Quick and Dirty Tips for Better Writing
Although not just for teachers and not strictly about grammar, this is a help website that provides well-researched answers to popular grammar questions. It is also available as a podcast.
One Stop English
Some materials are free, even more are available by subscription. Grammar section includes a reference guide, teaching methods, and games that are listed by clearly marked levels.
Learn English – Feel Good
In addition to grammar worksheets and quizzes, the section on phrasal verbs is very helpful. The verbs are listed alphabetically and are defined in simple English.
Perfect English Grammar
Along with the usual quizzes, this site offers clear commentary on a range of grammarpoints using videos and PDF’s.
Really Learn English
In the Easy English Grammar section, students are presented with clear and extensive instruction on all parts of speech and their usage. The examples and illustrations are especially helpful.
Offers grammar worksheets and printables for teachers as well as a teacher’s forum.