i think that the wiki is very close to being a Digital Book format. It seems to be very suited to browsing etc. Though organisation is always a problem. and it is never very well suited to image only Picture Book styles. One often has to resort to the ugly image gallery format in order to present pictures.
I have been trying to think of ways to solve this... to create for myself some ElegantMedia solution to creating a DigitalSketchbook.
Technology solutions: