I found 3 books that I would call essentials for any first-time mom, or any veteran mom who hasn't read them and is interested in a good read.
The first and probably best known book was What to Expect When You're Expecting.
This book is in it's 4th edition. I can remember seeing it in my mom's bookshelf when my sister was born. It really has a lot of good information and resources.
It offers a great breakdown of the various aspects of pregnancy. The What to Expect website is excellent as well. It even has a neat section for dads-to-be.
The next book that I think is a MUST for pregnant women is The Girlfriend's Guide to Pregnancy.
Belly Laughs by Jenny McCarthy is another entertaining book. It doesn't have quite as much
I haven't read On Becoming Baby Wise, but this method of establishing a feeding and sleeping routine
Parent Wise website, and it sounds like a fairly common sense method. The idea behind the method is to establish a pattern of eat, wake, sleep. You keep the baby awake more after feedings during the day to help the baby sleep longer at night. Amazon has used copies of the book for cheap. I am going to be borrowing a copy of the book from the co-worker who recommended it, so I'll have more of an opinion later, but if it gives me even a few tips for helping baby sleep through the night, it would be worth a used copy!