I'm in the process of making an automated etch-a-sketch. A user can select a black-and-white bitmap in a PC program I wrote, and it will send the signals to the arduino to draw the image on an etch-a-sketch.
I got the idea when I read these two articles: http://www.makingthings.com/projects/drawbot and http://instruct1.cit.cornell.edu/Courses/ee476/FinalProjects/s2004/jml66/EAS_final.htm
Progress so far: Software and Proof of Concept: http://video.google.com/videoplay?docid=4718591611921278678&hl=en
Stepper Motors Attached: http://video.google.com/videoplay?docid=2874964406552030776&hl=en