Gesturefy - Customizable mouse gesture addon, which supports over 40 different actions. Features:
Freeplane - Freeplane is a powerful and free software for building mind maps.
Easystroke - Easystroke is a gesture-recognition application for X11.
Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.
Strokeit - StrokeIt is an advanced mouse gesture recognition engine and command processor.
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.