"BallMageddon is an all LEGO scrolling sign that uses 2-inch diameter DUPLO balls as its display element. Seven builders, 11 NXTs, over 800 DUPLO balls, and many 1000's of LEGO elements.
Each character took a bit over 3 minutes to display. This was shown at BrickCon 2011, at the Seattle Center on October 1-2.
BTW: The final "BrickCon 2011" segment took approximately 45 minutes for the contraption to display in real time."