METEOR BLOCKS
Simple collaborative voxel editor by Sashko Stubailo lets you create and remix scenes made of blocks for fun. Each scene has it’s unique URL, so anyone with this link can edit the scene as well:
The friendliest collaborative 3D pixel editor!
Meteor Blocks uses the Meteor web framework and X3DOM together to create a collaborative 3D scene editor.
When you want to collaborate, just send the URL of the scene you are editing to someone else and they can edit it with you. When you’re done and you want to save a version of your scene, just click Publish and it’s enshrined in history.
Try it out for yourself here
Sashko also has a Tumblr blog here