To my mind this link http://lyricstraining.com/ is very  interesting. Firstly, because there are a lot of hits of music, which we are listninh every day on TV programs. Such sistem help to us improve our listening skills. Also, it help to us with our  grammar and we can without trouble memorize new words. This exercise does not take much time and it very funny. I advise you to use this link for you study of English.