Ronn Kling just published his 2008 IDL Christmas Card. This year’s card is a “snownado”, a tornado of snowflakes which interact with 3-dimensional objects. The code demonstrates how to efficiently move around many polygons in object graphics. From Ronn’s description of the card:

If you are looking for a way to visualize rapidly moving 3D objects then this card may be a good starting place.

Check out previous year’s Christmas Cards also, they are all very interesting. Direct download.