On This Day in Christian History by Robert J. Morgan
On This Day is set up like a 365-day devotional. Each day has a short, 1-page story about people in Christian history which is an easy way to introduce some of these martyrs and heroes. I think it would be especially inspiring for someone in ministry or missions who is or has the potential to encounter tough situations. Many of the people in this book died for their faith; others perservered through amazing situations to create profound changes.
Especially helpful as a devotional tool is the Index of Topics in the back; however, adding an index by person would have made it a useful tool for research also.