Just a quick plug for The Broken Land (originally published in the UK with the much better title Hearts, Hands and Voices), by Ian McDonald. McDonald is one of the great underappreciated science fiction writers of the twentieth century and this is one of his great, underappreciated novels. It's a biotech parable for the Irish Catholic/Protestant conflict, and the bones of that conflict are fleshed with one of the saddest, funniest, strangest stories I've ever read. Start with the Ancestor Tree, on which the heads of the recently dead are spiked, where their brains are kept alive and linked into an (ahem) neural net that makes an oracle out of the combined wisdom of all the dear departed. When the ancestors grow old, the bark grows over their eyes and they go into a dreamtime of bio-computational fantasy. There's an adventure story in here, and a coming of age story, and a lot of deeply kinky biotech thinking, and some of the most poetic prose I've ever read.