I really liked tikatok.com. I think this would be great for kindergarten because it has a lot of book already laid out and the children just have to fill in things to make it their own. It also gives the students an option to start from scratch. Our students would love to publish their writer's workshop books here. It also gives you an option to buy an e-copy and a hard copy of the book you created, which I am sure parents would want.
I love bookr. I think it is much easier for kindergarteners to use than tikatok.com. I think I will use this when we study mammals. I know the children would love to publish a book on bookr and I could share it on my blog. The only problem with bookr is in order to find the pictures, you must spell correctly when typing in the tags. Since many kindergarteners spell based on sound, this would be an issue for them.