Fire Upon the Deep, by Vernor VingeRead about the other books on the list.
Vinge is the computer scientist and author who first coined the term "Singularity" to mean the rise of superintelligence. In his most celebrated novel, he explores civilizations that are headed toward such Singularities, though they haven't quite made it yet. Still, they've set up quite a successful galactic democracy, full of aliens, AIs, and various combinations of both. Everything is zooming along at lightspeed, when they're menaced by a post-Singular consciousness/creature/disease that turns all matter into molecular sludge and wants to take over all available minds. This is a must-read.
--Marshal Zeringue