e-Books

Found out that many of my friends who are parents do not know anything about children e-books. My first exposure to e-books is Tumblebooks via NLB's eResources. I was not very impressed at that point in time as it requires much effort to register and login. By the time I was at the first book, I have decided to check it out another time which I never did. : (

When I next encounter Tumblebooks, I was at NYPL children's site. I had a great time clicking on some of the books : ) !! Here's the link :-
http://www.tumblebooks.com/library/asp/home_tumblebooks.asp

If you have come across any other great sites for children e-books, do let me know. Would like more people to enjoy them.