Kinopio - Thinking canvas for mind mapping, brainstorming, and moodboards
Kanboard - Kanboard is a free and open source Kanban project management software.
Excalidraw - Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.
Wrike Scrum Boards - Wrike Scrum Boards is an online virtual whiteboard that allows individuals and team members to streamline their agile practice at every step.
WBO - Realtime collaborative whiteboard
Birabo - An effortless collaboration tool for teams