LookyBook is a great resource for sharing high quality picture books with students via the Internet. I recently read about this tool on Kevin Jarrett's blog and I agree with him that it would be a great site to use with an interactive Whiteboard. You can access the books and even embed them without signing up for an account, which is a bonus when working with elementary students. Whenever you can utilize a tool without having to sign-up 25, 50, 100 students it is a definite plus. However, in case you are wondering, registering does allow you to comment on books, much like writing a review, as well as create your own bookshelf of books from their collection.
I have embedded a book below to show how this works. If you click on the eyeballs it will show you a larger version of the book. Of course, you could go directly to their site and view the same book but I always like the option of being able to embed content into my own sites such as a Wiki, blog or class homepage because it means my students don't have to learn a new URL just to access the content.