Based on my last post, Zuil and Lope engaged in a lively conversation about "flow charts", apparently also called "Sankey charts" in some circles. Here is an example Zuil found at the EIA site:
Zuil commented that
Though often difficult to draw, Sankey diagrams are IMHO unbeatable to represent any type of lossless flow (energy, money, fluids, etc).
I mostly agree: flow charts are great at tracing flows, and it's easy to figure out proportional sources and uses from this example. Moreover, as Lope suggested, it's fun (to read).
But... the data content of this chart is lower than that of the network graph or the Marimekko. Imagine removing all the lines (arcs) in the network graph: that is what the flow chart includes. It achieves more readability by simplification.