I like the way The Reading Nook is organized. I love young people's books, and if I ever set up a site with all my favorites, I'd want it to look something like this.
I haven't looked at all the books reviewed there, but I do see that it's missing three of my favorite math story books: The Number Devil, The Man Who Counted, and The Cat In Numberland. It does have a number of the Anno books, Quack and Count, and Demi's One Grain of Rice. I reviewed most of these books in my post on my favorite math books. You can also find reviews of great children's math books at the Living Math site and at the Love 2 Learn 2day blog.