Explain Everything - Explain Everything is an easy-to-use design, screencasting, and interactive whiteboard tool that...
Xmind - Xmind is a brainstorming and mind mapping application.
Microsoft Whiteboard - The canvas where ideas, content, & people come together.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Conceptboard - Instant Whiteboards for Teams & Projects
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.