Ebook: GPU Gems 3

Though I had no time to read most of the articles, I can say that this book is even better than GPU 1/2. It is still more narrative than educational (comparing to ShaderX series), but nevertheless I got useful material from it.
For example, the methods for ray-marching (multiple robust reflections and refractions chapter) are going to be used in our company.
I would recommend it for all professionals in 3D graphics, image/video processing and GPU (GP GPU) computing.