A little bit "out there" but I've been impressed with 'Dry Erase: Infinite VR Whiteboard'[0]. You get far more space to play with in a virtual environment than you can get on a screen. This would be killer if it supported multiple users over the internet, which is possibly being considered by the dev.[1]

[0] http://store.steampowered.com/app/585040/Dry_Erase_Infinite_...

[1] https://steamcommunity.com/app/585040/discussions/0/14584554...