Great idea Agiel - I think procedural materials and atmospheres are a great idea. A way to do this that might work is to have everybody start with the same scene containing a single object (e.g. a rock, tree, terrain, etc) and then have everyone apply their mats to the same object. I constantly struggle with rock, bark and groundcover mats. Another area that would be great for a group think is lighting - starting with a common scene - who can apply the most realistic or unusual lighting.