Well, this could be a type of
fiction, usually
anime-styled, in which multiple
authors write, usually signing up in a
queue. It could also be a specific
story being done in that fashion. Or it could be the
site (http://improfanfic.com) that started it all. ^_~
Oh, and just because it says
fanfic, doesn't meant that it's a
fanfic. Most have
original characters.