Yeah, so, I made this program that reads in a .jpg file, smooths it out a little bit, adds a bit of noise to excite a ditherer, and spits out something like this file. There is a simple key to that file. The p means pink, the o means orange, the x means black, g's mean green, and periods mean leave it white! What you do is start on the left side, and scan to the right. (sorry lefties, I'll work on a variation for you real soon now!) What you do is send that file to a printer, then color it in. It would probably be very fun to create greeting cards and things like that.
The program also generates a jpg preview and a mini report that tells you how many pen swaps you'll have to do per line. You see, you can make ultra-realistic-looking renderings with a high degree of dither, but it's aggravating to have to swap markers 3,000 times. So, instead, you can dial up a blurriness factor (2-d gaussian filter) to reduce the detail.
Here are some previews of pictures.
This is my friend Liz:
Click here for the print-out you can color
This is Noam Chomsky:
Click here for the print-out you can color
This is a cute picture of two doggies:
And finally, my friend Steve: