Howard Hendricks is one of the guys whom God has used to give me a hunger for teaching and discipling others. Hendricks has shared the Word in more than 80 countries around the world. He has also written more than a dozen books on family life and Christian discipleship. The Discipleship Library has quite a few of his messages available including a 5 - part series on the Dynamics of Discipleship. And I would highly recommend getting The Seven Laws of the Teacher (on DVD) as a resource in discipling your teachers and leaders.