You could do this through the students if you wanted as well.....  We have so many different levels of talent here....  You could post a song and ask what key it is in and someone could tell you.  From there you could go to work.  Report back periodically for feedback and direction.....  Just a suggestion.  I have tried it in the past, and found it to be very helpful.  I don't have the greatest ear for music, but once I know a key, it sure makes transcribing a lot easier.
MJ