I highly recommend Shepherds After My Own Heart, by Tim Laniak, for those serving in ministerial positions and/or interested in the biblical theology of the shepherd/sheep/flock metaphor found throughout the Bible from Genesis to Revelation.  I also recommend this book for anyone interested in the study of leadership, Christian or otherwise.

Dr. Tim Laniak is an OT/Hebrew Professor at Gordon Conwell Theological Seminary.  His book represents an exhaustive study of the shepherd motif/metaphor in the Old and New Testaments, as well as ancient near eastern cultures.  

The analogies of a shepherd, under-shepherds, sheep, goats, rams, ewes, and lambs provides a rich medium in which to help communicate the biblical theologies of 1) leadership, 2) the sacrificial care and concern of God for His people, 3) the visible church, 4) church discipline, 5) the role of human ministers, 6) the saving work of Christ, and 7) eschatology and judgment. 

The book is written to accommodate both the common laity as well as advanced biblical scholars.  Someone with little or no knowledge of the Bible will appreciate it, as well as the Biblical language expert.  

In addition to its "standalone" value, the book has an advanced bibliography and detailed indexes to serve as a reference text for future exegesis work and sermon preparation.