Bukkit

Hey,
I have found your plugin and I like it. And now i wanted to create a server with my team(6 persons).
But we would like to have little minecraft world planets.
This planet would have an as similar structure as the vanilla minecraft world, but it would be a ball.
Furthermore, there could be configurable stages/shells of this planet, for example:

There are 3 shells.
First has only dirt and stone.
Second has only stone and coal
Third hast hast only coal and lava.

And then everyone would get a planet.
Please think about our idea. If you have questions, feel free to send me a PM.
Yours,
Vincii