My attention has been drawn to a most unusual project. A group of people are trying to write a bel canto opera based on a Sherlock Holmes fanfic. I’m not really sure what I think of the idea of fanfic, which I have avoided to date, though I must note that persons I consider almost entirely sane are quite committed to the genre.
For the curious, the details are here.
operaramblings 
That’s going to be interesting because Lyric Opera of Chicago has also commissioned an opera called Bel Canto, based on the novel by Ann Patchett. Someone is going to have to back down over the title.
I read a bunch of Battlestar Galactica fanfic back in 2008 or so. What I found most interesting about it was how people were creating these texts that had this odd relationship to the original thing – sometimes taking a concept and filling in the blanks or elaborating, sometimes reading the same thing in completely different ways, or rewriting a narrative or a set of relationships in a way that was deliberately antagonistic to the original.
Most of the writing was pretty bad though.