Incredible work by Sohrab Esfehani.
Stunning texturing work by Timothé Claeys.
Some examples of a pixel art style, achieved by combining the Toon shader (ramps ->Base & Specular Tonemaps) with negative Camera (AA) samples. More examples here.
Snow shader workflow by Jarrod Hasenjager.
Great work by Sergey Konovalov.
POTA [POLYNOMIAL OPTICS TO ARNOLD] is an OPEN-SOURCE camera shader for the Arnold renderer based on SPARSE HIGH-DEGREE POLYNOMIALS FOR WIDE-ANGLE LENSES .