OpenBoard - The OpenBoard software is an interactive white board software.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Conceptboard - Instant Whiteboards for Teams & Projects
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
IDroo - A shared whiteboard for use by multiple Skype-users simultaneously. Features
Slack - A messaging app for teams who see through the Earth!