Last year, I ranked the Student Sites of the Oxford University Press at number three on The Best Internet Sites For English Language Learners — 2007 list. They have hundreds of great online EFL/ESL activities for all levels of learners.
Since that time, they’ve added several additional excellent activities for English Language Learners.
I especially like their “Listen and Write” exercise, where words are spoken and students need to write what they hear.
I’m adding the links to my website under Favorite Sites.