My two favorites were:

The Birth Partner by Peggy Simkin. This book covers ways to support your partner/wife/baby mama throughout pregnancy, with insight into what's going on physically and emotionally, and also goes over how to help out during labor and delivery. I found it to be a really thoughtful approach to the support role.

Be Prepared: A Practical Handbook for New Dads by Gary Greenberg. This one has a bit more of a humorous approach, but also gives you some ideas on what to do to get your home ready for a newborn and then some stuff you can do with the baby in the first year or so after she's born.