how about this:

if this topic is picked, a problem is picked at random by me, and the contestants must write a program to solve it. i want the problem to be picked randomly at the moment the contest starts so no-one has a head start.

example
problem: given a grid of new-york-city intersections, find the fastest route to point x. (the grid will be in raw text, not as an image file, to make things easier)


that's not the best example i can come up with, but i hope i've conveyed the message. what do you all think?