I know that it may not fit exactly in this category but I believe THE CULTURE CODE by Daniel Coyle is fantastic for developing leaders and a culture for your leaders to be successful in it. I am working my way through it for the third time.
Also in a little different area, but there is a TED talk called ‘The Power of Vulnerability’ by Brene Brown. It spoke to me a lot about some aspects of leadership that may not be so obvious. I have had several young ladies that were good leaders for me start with this.
@Sam Allen Lead for God’s Sake is a great book! Everyone should read it at some point.
I am a history guy so George Washington Leadership by Richard Brookhiser really spoke to me. There is a chapter that talks about the army retreating across a narrow bridge while being attacked and soldiers had written home about how Washington was on horseback above everyone else like a statue until every soldier retreated! Courage under fire!