vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
share.link - A fast and easy way to organize and share your links
Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.
Spectrums - Share what matters to you.
Freeplane - Freeplane is a powerful and free software for building mind maps.
netboard.me - netboard.me allows you to combine all your content into a beautiful single web page.