This is a very good source of different exercises for ESL learners with the help of computer. It provides computer lessons, writing lessons, grammar lessons and reading lessons, and also interesting games to practice English.
It's a free site for English learners.You will find free vocabulary sheets, English grammar sheets and English exercises.This site has about 2 million visitors a month.
As we are future teachers I think this information can be very useful,because we always need a bunch of activities to conduct a lesson and to keep the whole class motivated.
I recommend this site both for teachers and learners because it suggests effective and useful material for English for various purposes as well as lesson plans and intersting ideas for teachers.