Choosing Single Motherhood: the Thinking Woman's Guide - The author of this book is a woman who has had two children on her own.  She covers numerous methods of becoming a parent on your own and also includes input from other "choice mothers."  An excellent book!

Single by Chance, Mothers by Choice  - I must admit I have not yet read this one, but it was recommended to me by a friend who is currently carrying her first "choice child," and it is next on my list of reading material.  I promise to update this once I finish the book.

Adopting on Your Own  - An EXCELLENT book!  I am currently in the midst of reading it, and have found every inch of it useful so far.  The author has adopted twice on her own, the first time being back in 1984 when adopting on your own was almost unheard of, and the second more recently.  This has obviously left her with a vast array of knowledge on the subject.  So vast that she runs an adoption workshop in the Boston area.