Zim Wiki - Zim is a graphical text editor used to maintain a collection of wiki pages. Each page can contain links to other pages, simple formatting and images.
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.
Scribbleton - The little personal wiki.
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
MyInfo - MyInfo is the most versatile organizer for Windows
Slack - A messaging app for teams who see through the Earth!