Guillaume Decaux has such variety in his work, you would think that he has multiple personalities. Visit his site and spend some time, there are multiple galleries, sketchbooks, archives, live sketches, and even a silent animated film. The talent does not end with this artist.
It was very hard to come up with just one piece of artwork that I liked, the choices are endless. His live sketches are awesome too; be sure to check out his Quicktime videos that displays his multi-faceted abilities. Of course, you could also check out his SketchBlog