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.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Mindomo - Easy-to-create and share mind maps, concept maps, task maps and outlines. Mind mapping software for Web, Desktop, iOS and Android. Mind map with us for free!
Slack - A messaging app for teams who see through the Earth!
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.