Many of these sites also have bonus material such as author interviews, articles and news.
If you want to take it a bit further with the kids - some of these sites also offer fun learning activities to go with the book of your choice! See ABC Jenny and My Little Story Corner.
And don't forget, your local bookseller (especially if you are fortunate to have a specialized children's bookshop) is always willing to give expert advice!
So best wishes in your adventures in children's book land!!