Nifty - Manage projects, work, and communications in one place.
Xmind - Xmind is a brainstorming and mind mapping application.
ZenHub - ZenHub is how the world's best software teams work together. Trusted by NASA, Docker, and Rackspace. Start free today!
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
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.
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.