Another outstanding example is Norman Conquests, a trilogy of comic plays by Alan Ayckbourn which show the same events, with each play limited to one setting (the dining room, the sitting room, and the garden) with the events which appear onstage in the other plays occuring offstage in the play under production.
The revision of texts on a wiki would allow parallel texts to arise even from what was originally a linear text. Let's say that a reader did not like the way the original author ended the novel. The reader could changing the ending if the novel were on a wiki. Let's further imagine that the original author preferred the original ending. The reader's alternative ending might be rolled back. But before doing so, the author might preserve the reader's alternative ending in a new wiki page, with a link to this page from the page containing the "real" ending.
Readers could read the narrative according to the conventional fashion, from start to end. If the novel is good, when they come to the end, they might wish there was more to read. They could then go to reader-created parallel texts which cover the same period an in the authoritative text.
These parallel (perhaps alternative would be a better word) texts might just cover a single chapter, diverging from the original text, and then converging back, or might contain irreversible differences which force the entire narrative into a new direction, in a sense a parallel universe.