Greg Egan recently designed another of his universes. This one is named "Orthogonal" and is based on symmetry between space and time (instead of the Minkowski space-time the world is based on the 4-dimensional Euclidean space):

http://www.gregegan.net/ORTHOGONAL/ORTHOGONAL.html

A beautiful universe; the role of light is really interesting; very interesting biology with innovative gender and procreation scheme (and more or less familiar social patterns refracted by this physics and biology). "The Clockwork Rocket" appeared this Summer and is the first novel of the planned trilogy, I've just read the Kindle edition, liked it a lot.

"A Fire Upon the Deep" (a 1992 novel):
http://www.lib.ru/INOFANT/WINDZH/firedeep_engl.txt

"Пламя над бездной" (один из переводов):
http://www.lib.ru/INOFANT/WINDZH/bezdna.txt
( more links )