How to Win Friends and Influence People
by Dale Carnegie is a classic on how to get along with others. What you may not know is that the end of the book has a section devoted to married couples. This book is a must-read for couples, although some concepts in the book are a little outdated.
Love Life for Every Married Couple is a biblically based book written by a family physician. This book contains simple, easy to use concepts to improve, and if necessary save your marriage. The end of the book is titled "how to save your marriage alone." It includes sections on intimacy, communication, sex, and friendships. The "BEST" plan described by the author is an effective way to improve your love life. This is a great book, and highly recommended.
The Dirty Half Dozen is a quick read, and really makes you look at your relationship from a long-term standpoint. This book is written by a psychiatrist, but it is simple and straight-forward. You can read this book easily in an hour- a big plus. Currently it is out of print; try looking for a used copy at Powell's Books.
Every couple should have a good book on the physical side of marriage. I recommend The New Joy of Sex as a good overview, although many topics included in the book don't pertain to married couples. For men, Sex Secrets is good. Also recommended is Secrets of Better Sex.
Do what Dale Carnegie recommends- don't neglect the physical side of
marriage. Get a good book on the topic, and read it!