This would allow forum members to have or create their own private kaban collaboration board.
Each forum member can create tasks and then move them around a grid.
Having Kanban would literally set Xenforo on fire.
This would be the coolest add-on. People could start collaborations and tasks.
Kanban is proven and better than GTD (Getting things done).
If it integrates well with the XenCarta Wiki + 3rd Blog solutions + 3rd party CMS, this will be the hottest add-on.