For those of you who are currently pregnant with twins (I can actually say that. It is so common, now.), I have a great book for you.
TWINS 101 - written by Khanh-Van Le-Bucklin, M.D., M.O.M (Mother of Multiples)
I just read the book. It was helpful as well as insightful! I wish I had read it before having the twins, it's a great beginning to a new adventure-twins. It was an easy read, with helpful info and tips, from conception through pregnancy and into the infant stages.
The book was written by a pediatrician who has a set of twin girls, herself.
I bought it on Amazon.