You will find numerous resources for English for Speakers of Other Languages online. Use a search engine such as Google or Yahoo to find what you are looking for.
Looking for free online grammar lessons with exercises? See the Learn English Today site. You'll also find idioms here along with word games and fun activities.
Want to test yourself? Choose your level and take some free online quizzes.
Review your grammar here: tense, adjective, adverb, and noun practice.
This page will link you to several great sites for improving your vocabulary.
Join a free ESL Discussion Board and ask your own questions.
Take tests, study lessons, join discussion boards on the Eclectic English page.
Say What? is an online ESL magazine with articles, quizzes, and games.