The Phaidon Design Classics book set is now available as an iPad app. Considerably more portable than the phone-book-like 3-book and much cheaper at $19.99 rather than $175. It contains over 1000 great design objects from "cars to chairs, tableware to cameras, from toys to airplanes."
The iPad really is the perfect venue for coffeetable books. I hope Phaidon and other publishers will consider the iPad and release other books in digital form.