Mixbook - this site is my favorite. It allows you to really customize your book.
Shutterfly - love this site too. Offers custom features, but not as much at Mixbook.
Walmart - believe it or not, Walmart has a great photo book site with quite a few options.
Creating custom photo books can be a fun way to tell a story of your event. Whether weddings, graduations, newborn births, and just a yearly family book, digital photo books are awesome. Do any of you have another favorite site you have used to create a photo book? Let me know. I would love to hear from you. The example below is a book I created on Mixbook.