Getting to Yes: Negotiating an agreement without giving in by William Ury

Basic life skills.

Difficult Conversations: How to discuss what matters most by Douglas Stone, Bruce Paton and Shelia Heen.

Should be taught in middle school.  And certainly in business school. 

Finite and Infinite Games: A vision of life as play and possibility by James Carse

Possibly my favorite book, ever

Five Invitations: What death can teach us about living fully by Frank Ostaseski

Important and real.

We Learn Nothing by Tim Kreider

Hilarious, unflinching, insightful.

The Course of Love by Allain de Botton

Required reading for anyone in a long-term relationship