Animated GIFs: The E-Book
This idea died after a little investigation into what's possible with e-books. To begin with, you have several commercial e-book formats, either based on PDFs or something similar. These are imaged pages, as opposed to dynamically generated ones that could pull up other media and incorporate it into text.
The open-source "EPUB" file in theory works like a browser and could assemble pages with animations. No one is actually doing that because of (i) the variety of hardware devices EPUBs would be loaded on (ii) general unreliability.
It's a shame because it would be nice to have some books on the subject of internet-based expression that weren't dependent on verbal descriptions of unseen processes. Unlike web-based publications, books force you to stay within their confines and confront the points they're making, rather than letting you wander off into the link wilderness.