Theres a nifty little program that can generate a map of the minecraft world.
If its possible to access the world data, it would be interesting to see the changes to the map as building goes on.
First time the server is booted up to see it untouched and then perhaps every day or two after.
You could drop the maps onto here for everyone to see as we go... although if you were attempting to build something secretly it might hinder your plans!
Any thoughts on this?