For instance, here is an application I've talked about before, which one day I would like to build, what I have called a Content Engagement System, though I don't know if I really like this terminology. As with a standard CMS platform, a logged in user would be able to create a textual context, with associated images, video, documents... Within this textual context (which I will start referring to simply as 'context' since this translates roughly as 'with text', right?), another user can identify a phrase, and rather than linking out, the way a standard hyperlink works, link in. Sounds kind of odd, but this is essentially like adding a comment, except the comment is associated back to a phrase within the original context. In HTML terms, this is similar to a link to an anchor within the same page, and in a textbook we would identify this as a footnote.
Okay so far. A blogger posts something, which is then considered canonical, after which anyone else can add footnotes, and these offer an alternative view. A use case then: say I am writing a novel, which is serialized in weekly installments. The math is something like, 1000 words/week = 52,000 words/year, which then gets bundled up into EPUB or PDF and flogged off on Kindle, Smashwords or whatever. The idea is to create demand through serialization, then capitalize on the demand with the actual content.
But, and here's the thing. I want to engage my audience. And but, I want to entertain my audience. And but, a vocal minority within this audience typically demands something edgier; or racier; or, well, smuttier. Which, for the purposes of illustration, let's assume is not really my style. So what I want to provide is the canonical safe version of my novel, and a mechanism, a backstage, which allows the audience created by the canonical story to add (share) their own non-canonical additions to the story, which can then be linked to from within the canonical context as an alternative or supplement. This is similar to a literary parallax (events viewed from multiple vantage points).
More on this at some point. This is an idea I really want to pursue... but it is hard to articulate, so bear with me.