Here's an idea, combining the Intent-based event model in Android with Infinite Jest style hyperfiction. What if you wrote a short novel, or rather series of short novels, and instead of using ePub or PDF or whatever, you used an Android application, targeting people's Android devices. Each novella would be say, 15,000 words long, but they would communicate with each other using intents to create footnotes out of a shared index, distributed over multiple texts. So you install one book and you get a 15,000 word novel. You install two books, and you get two 15,000 word novel, each of which has 5,000 words worth of footnotes. You install a third book and you get three 15,000 word novels, each with 10,000 words worth of footnotes.
Would you have to write all 4 concurrently, though?