Conforti, Mark. Clergy Mentoring: The Tie That Binds. -- This book is available in Kindle format only. Conforti and I share a very similar philosophy of mentoring. This is a self-published book based on his doctoral work.
Mason, George. Preparing the Pastors We Need. -- This book looks at some pilot projects that were completed out of a grant from Lilly. These projects were focused on one's first 5-years in ministry and how to set up pastors to succeed.
Reese, Randy and Robert Loane. Deep Mentoring. -- Reese has written another book as well (Spiritual Mentoring). Both books take a look at the character formation side of mentoring, which I believe is significant. These are good books, but are more supplemental compared to some of the others on this list.
Sanders, Martin. The Power of Mentoring. -- This is a good basic overview of mentoring.
Williams, Brian A. The Potter's Rib. -- Williams' book is one that I find highly helpful. He does write from a Calvinist perspective at times, but it is a good work.
Wright, Walter. Mentoring: The Promise of Relational Leadership. -- This is a short, but good book on mentoring.
For additional resources on mentoring - including sample accountability questions for the mentee/mentor and specific reading recommendations in the areas of character formation, pastoral/vocational identity and pastoral skills – click here.