And sticking with the Oulipo theme: I've probably read this half a dozen times already, but I still spot new stuff every time. This is Perec's tour de force of wordplay, plotplay, constrained writing, and just general cleverness. One of my favourite books; I'm still indebted to the English teacher who lent me his copy many years ago...
ISBN 1860461468. Search for this book on Wikipedia or isbn.nu.