Perhaps a stupid idea, but could the same engine used to help us learn how to properly write Chinese and Japanese characters be used to teach Chinese and Japanese people how to properly write English words? With 52 upper and lower case characters this seems rather trivial to implement. Add a vocabulary list for the most popular English textbook series in China (Longman New Concept English) and example sentences from that textbook, as well as display videos inline (the textbook videos are all on Youku) and you might have another success on your hands.