Writing.
http://esl.fis.edu/learners/writing/index.htm
http://www.autoenglish.org/writing.htm
http://www.meredithsuewillis.com/writingexercises.html
https://owl.english.purdue.edu/exercises/
http://www.dailywritingtips.com/10-writing-exercises-to-tighten-your-writing/
Speaking.
http://www.englishstudydirect.com/OSAC/langacls.htm
http://www.autoenglish.org/speaking.htm
http://www.eslflow.com/speakingandcommunicativeicebreakeractivities.html
http://www.myenglishpages.com/
http://es.scribd.com/doc/33773905/Speaking-Exercises-Eso
Listening.
http://www.esl-lab.com/
http://www.esl-lab.com/short.htm
http://www.saberingles.com.ar/listening/index.html
http://www.carolinebrownlisteninglessons.com/
http://www.examenglish.com/FCE/fcelistening.htm
Reading.
http://www.englishforeveryone.org/Topics/Reading%20Comprehension.htm
http://www.rhlschool.com/reading.htm
http://www.saberingles.com.ar/reading/index.html
http://www.abcteach.com/directory/languages/spanish/reading_comprehension/
http://www.google.com.mx/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=6&ved=0CHEQFjAF&url=http%3A%2F%2Fwww.literacy.uconn.edu%2Fcompre.htm&ei=pK0JUPfSFeS42QW0qvzJBw&usg=AFQjCNFTQrJ4p925SgcgMq8Z2p9OHNQtmQ&sig2=RzITAp96HJORbbY6bocP5A
