Some internet websites that can help with learning or teaching English. All are free
http://www.starfall.com/
http://www.de.mingoville.com
http://www.learn-english-online.org/
More advanced:
http://www.englishpage.com/grammar/
A website I have used a lot is abcteach.com. It is a subscription service, but I have found it worth every dollar ($35) and then some.