Games:
http://gamestolearnenglish.com/
Grammar exercises:
http://www.eslcafe.com/grammar.html
http://www.esldesk.com/
http://englishmaven.org/index.html
Idioms:
http://a4esl.org/q/f/x/xz49mjc.htm
Listening exercises:
http://www.esl-lab.com/index.htm
Pronunciation and spelling practice:
http://www.learnenglishfeelgood.com/listening/index.html
Various:
http://larryferlazzo.edublogs.org/2011/08/07/the-best-sixteen-basic-sites-for-beginning-english-language-learners-revised/