Emotionally Healthy Twins: A New Philosophy for Parenting Two Unique Children
This is one book that you simply must read! Written by a twin who has twins, and is also psychotherapist.

Here's some information from Amazon.com:
Drawing on her unique experience as a twin, the mother of twins, and as a psychotherapist, Dr. Joan A. Friedman outlines the seven key concepts for helping twins develop into self-realized, unique individuals and offers parents specific strategies for each stage in their children's growth. From how to set up the nursery to handling playdates and extracurricular activities, from deciding on same or separate classroom education to encouraging grandparents and other family members to think beyond the pair to see individuals, Emotionally Healthy Twins will become the standard reference for parenting twins.

Read a review written by Rachael Towle during her twin pregnancy.

Two Snowflakes by Jennifer Miller

Here's some information from Amazon.com:
Is it true that no two snowflakes are exactly alike? Phina and Bella aren't so sure: They are often mistaken for one another! However, a chance encounter shows them just how unique and special they really are. Whether you're young or old, have twins or not, this frosty tale is sure to melt your heart.

About the Author: Jennifer Miller lives with her husband David and their identical twin daughters Josie and Anna in Cockeysville, Maryland. Jennifer is also the founder of TwinHappy.com, a website dedicated to informing, entertaining and bringing together the twin parent community.