Our designers frequently mock up designs for new features / versions of the site. They then get email responses that say X,Y, and Z (multiple times from different people). Sometimes they get conflicting X-1 and X-2.

With this I could see them sharing the wall with everyone and then getting collaborative feedback from all of the stakeholders.

What features specifically are you implementing? I would like undo, redo, step backward, step forward, and a better way to manage text.