I've been writing my own Sunday school material as I teach the book of James. I'm creating both a teacher's guide (the content to be taught) and a student's guide (preparation for interested students). I've finished the first chapter. You can either click on Bible in the menu above or click here.
"How People Change" by Timothy Lane and Paul David Tripp is an excellent book that every Christian should read. It describes the biblical process of change (sanctification) in such a way that everyone can understand God's plan. It reveals that God is not satisfied with merely changing behavior, but he wants to change our heart as well. It is especially good at looking at how people change during the difficult situations in life.