i.e. creating the outline for a book, adding pieces in temporary holding spots (cells) and shuffling those pieces around as chapters and sub-chapters start taking shape in the outline.
Keeping notes (references etc.) embedded in there.
TreeSheets rocks something silly.
My favourite thing is the ability to see the whole picture by quickly zooming out via mouse-scroll-wheel, and quickly zooming into a detailed view of any part when needed.
See the bird's eye view in the screenshot below. See an export of the zoomed-in image
here.