Bertrand Benoit posted on the forums about a wonderful VRay balloon material he is offering for free. Looks incredibly real to me, and ORANGE!
Following Javier’s great V-Ray procedural sand tutorial post, I’ve seen this rather cool video by Sascha Henrichs over at 3dtotal about the way he models 3d sand dunes using 3ds max patch grids. You might get a very nice looking sand environment doing a combo of both. Feel free to mess around with it.
ASGVIS 3D Artist and Trainer, Fernando Rentas, created the Vermont Verde Antique material in V-Ray for SketchUP Using basic material creation techniques as explained in the featured video tutorial Creating Vermont Verde Antique. Fernando was able to match the rich green color and unique light green and white veins by looking at a small sample of the marble. Check out the video below, it is very informative and the result is remarkably good.