I know we are in a gaming forum so I don't need to tell you about the hugely popular homebrew called Multicraft. If you don't know what it is its just like the incredibly addicting Minecraft created by Notch.
This mod for multicraft has a feature that a lot of sceners have been waiting for. Its the save feature. Grab the download for Multicraft here.
Here's a video of the game to give you an idea.