As we all know the biggest problem with minecraft is greifing and that the only surefire way to avoid it is to play single player maps. The problem with single player is that, well, its single player. Back in the ancient days before multiplayer there was an answer that solved both these problems: The Minecraft Community Level! It combines the collaborative and varied experience of multiplayer with the grief free advantages of single player.
Since the old community map had none of the advantages of the new blocks and doesn't seem to have migrated to the new forums I have taken the liberty of creating a new Minecraft Community Level. I've started by making a modest house with a furnished basement and a swimming pool.
If you want to add to the level first make sure no one is currently building.
Next, post your intention to add to the level and an estimated time until completion.
Click on the previously posted link and build your masterpiece.
When finished, post or edit to inform everyone and write a short description of what you made. Be sure to include a link to your new version.
If anyone greifs or builds something extremely obnoxious simply ignore their post and add to the previous posters backup. I will try to keep an up-to-date backup on my id=3 in case too many previous posters have overwritten their version.
It's just a different type of level. It's not trying to be multiplayer. It's like having a somewhat less fun public server except that you won't ever get greifed. Also you can use memory hacking to make really cool stuff, so give me 15 minutes while I go make a waterfall.