By authors' relationships

By author - but organized based on the relationships between the authors. A sort of six degrees of separation pattern. (I wonder who would be the centre, the Kevin Bacon? In my bookshelf, Neil Gaiman is naturally in the centre, because the Absolute editions w/ bookends have to be on the sturdy middle shelf. But probably someone like Shakespeare would be an excellent nexus... or in my case, perhaps Lord Byron.)

Some examples: Siri Hustvedt with Paul Auster and Moa Martinson with Harry Martinson are obvious choices. Emma Bull and Elizabeth Bear and Ellen Kushner are friends, and they are in turn friends with heaps of other excellent writers. But there are also connexions such as: obviously Stephen Fry should stand next to Oscar Wilde.

Like many other systems, this would probably grow to require a shelf in at least three dimensions. And/or it could probably be combined with an intertextual system.