Second Wives Club is a website with great information for women with stepkids, including essays and articles on everything from parental alienation to financial planning in stepfamilies to navigating family court and understanding stepfamily architecture.

In a five star review, they advise their users, "Read Stepmonster before you read any other book on stepmothering." They're doing a limited Stepmonster giveaway:

http://www.secondwivesclub.com/portal/forum/showthread.php?t=28199