How remiss of me. I should have mentioned this earlier: the State Library of Victoria's new website tracing the history of books through examples from its own collection: The Mirror of the World.
I'm rather keen on the Puss in Boots interactive (page turning, zooming and audio) and the incredible resolution on the Matthew Flinders map that lets you zoom up uncannily close.
It includes some of the finest and most remarkable books of all time - from cuneiform to Caxton, from manuscripts to William Morris to Nelson Mandela, via Shakespeare, Piranesi, Einstein, and the crazy old Hypnerotomachia Poliphili.
(Disclosure - I work there. So consider this as shameless promotion. But it's still a damn fine thing.)