Net Grammar has a series of fifteen units with sections on grammar, reading, writing and more.  The section that really stands out, at least to me, are the sections on Listening.   Each unit has a Listening section where the student can clearly hear a person talking.  While the student is listening they can answer a series of questions on the screen about what they are hearing.

I’ve placed this link at the bottom of the Audio Conversations category of the English For Beginners page on my website.