Add a reasonable error message for the likely case that someone tries to edit a chunk that the minecraft game hasn't generated yet.
Add the ability to set the block-type and the data modifier with a single object/call.
Code that generates a floating island with a jagged bottom.
Code that generates a "checkered" tube.
Code that you continuously feed coordinates to and at the end you ask it for a random one.
Code that generates a random hedge maze.
Code that generates the shell of a skyscraper.
Quit hardcoding the location of the world to edit everywhere.
Hardcode it one spot so I can unstupidize it later.