I have bought books from Amazon and Manning.com, mostly technical books. I have to say, I am so happy with the business model of Manning.com: - they offer good

I have bought books from Amazon and Manning.com, mostly technical books. I have to say, I am so happy with the business model of Manning.com: - they offer good quality books - they also offer a subscription where you can view all books and download one book per month - when you buy a digital book, they give you the book in several formats (kindle and pdf) - you can read the ebook in multiple devices O'Reilly should follow the same business model.