Max Barry's Machine Man is a disarmingly funny and light-feeling novel about an antisocial engineer who decides to create his own prosthetic leg after he loses his own in an industrial accident. Charles Neumann is an antisocial, technology-dependent scientist at a top secret military contractor's skunkworks. Dissatisfied with the prosthesis he is fitted with after he accidentally crushes his leg in a materials-testing machine, he sets out to create a better leg -- a leg that's so good you'd chop your own off to get it (this is also the battle-cry of the real-world open-source prosthetics movement). Which is precisely what he does.
What unfolds is a superficially simple, absurdist tale about a misfit geek who pursues a relentless and seemingly logical program of amputation and replacement. Barry uses this narrative to smuggle in a sly and insightful critique of the anti-human edges of the transhumanist movement, the place where transcendence of nature meets mortification of the flesh.
As with all of the best thought-provoking sf, Machine Man pulls this off without slowing down the action -- which involves some properly cinematic cyborg duelling and such -- and without sacrificing characterization. This is a really fantastic read and a thought-provoking one, too -- a great companion to such books as James Hughes's Citizen Cyborg.