Kingdom, Grace, Judgment: Paradox, Outrage, and Vindication in the Parables of Jesus This book is geared toward a popular audience, but Capon's work is reliable. This book is best at engaging the reader to experience the parables.
The Parables of Jesus: A Commentary (The Bible in Its World) This provides an encyclopedic approach to every parable. This is the place to start to get background information about any particular parable.
What Are They Saying about the Parables? An excellent introduction to the study of the parables including a historical overview as well as more recent approaches.
Re-Imagine the World A popularized and more concise edition of his insightful Hear Then the Parable.
Hear Then the Parable A technical and thorough commentary on the parables, but one that certainly has an eye toward how they would have been received in Jesus' time.
Stories with Intent: A Comprehensive Guide to the Parables of Jesus The most recent book on the parables, and, as the title indicates, it is comprehensive!