I like the explosion idea Acantarel posted. Though its kind of like the avalanche one that was just done. Using particals.
I also like the tornado idea.
A non animated challange would be nice, for those using 2d apps. Compositing and such. Like making a still photo of a rainy day or something. that could be done in both 2d and 3d apps.
one other idea. a wierd object is selected, (ex. - a belt clip for a phone) and the contestants have to make it into a convincing real world object. A building, car, boat, or something. The goal is to try and make the wierd object look like it belongs to the model created. The wierd object must look like the one given (shape) but could be textured to fix the contestants model
Anyone think thats a good idea?