Came across a great website containing tools and resources for English as a second language. For example, the site has 257 free English language quizzes covering grammar, usage and vocabulary for beginner, intermediate and advanced level English students.
Check it out: http://www.usingenglish.com/
I especially liked the reading comprehension test - see how you do. http://www.usingenglish.com/comprehension/46.html