Think out loud. It arranges itself.

Most diagramming tools make you draw. You have the thought, and then you spend the next minute finding the right box, dragging it into place and drawing a line to it. By the time the box is where you wanted it, the thought has gone.

MindMapX puts the keyboard first. Type a thought, press Tab for one underneath it, Enter for the next one alongside. The layout rearranges itself as you go, so the map keeps up with you instead of the other way round. When the shape of the thing changes, switch it: the same topics become a tree chart, an org chart or a real spine-and-bones fishbone without being rebuilt.