As of the latest Minecraft snapshot (12W40A), it is now possible to create superflat worlds with structures such as trees and grass. I still haven't found out how to create a superflat world with this setting - where is the option for this?
You can add structures such as trees and grass (and others) using the Customize interface. As of 12W40A, you have to use
To create a superflat world that also generates trees, flowers, and tall grass, use the following preset:
This will generate a world with a layer of bedrock, two layers of dirt above that, and then one layer of grass above that. Trees, flowers, tall grass, and so on will be generated. The trees will be fairly spaced apart.
Note that villages cannot be generated here, since they only generate in
If you want more trees, you can change the