The sudden baby-making flurry has precipitated this post. I think all five of these items are new-mom essentials (but still listed in order of priority):
1. 
The Womanly Art of Breastfeeding – This is the absolute bible when it comes to breastfeeding. Even better if you can attend La Leche League meetings because then you meet other moms with the same parenting values.
2. 
The Baby Book: Everything You Need to Know About Your Baby From Birth to Age Two by Dr. William Sears – As there are as many ways of parenting as there are parents in the world, it is critical to find resources with parenting values that feel right to you. Dr. Sears and his wife have raised five children and are adamant believers of attachment parenting, which is what felt/feels right to me. He will not tell you to let your baby cry. He and his wife have written many, many child-rearing books.
3. 
Natural Childbirth the Bradley Way by Susan McCutcheon – This is for the mom who is going for a natural (drug-free) birth. It goes without saying that it goes hand-in-hand with taking a Bradley class.
4. a baby sling – Bella practically lived in one for the first nine months of her life. I liked it because she could sleep and nurse very discreetly and both my hands were free. Also, since she was with me all the time, Bella rarely cried. I had a Baby Bjorn as well, which was ergonomically good for hiking, but I couldn’t put Bella down in it when she was sleeping because of the tangle risk.
5. a nursing pillow – put one under a nursing mother’s arms and watch all the tension drain out of her shoulders.