Sankey diagrams are a type of flow diagrams with differing widths of arrows that track where an initial amount goes.
They make for a great budget tool to see how your money ends up going. You can easily plug in your weekly or monthly expenses and paychecks or even put in your yearly W2 data to track our how your expenses and money have been going.
Sanekmatic.com is a great free tool to make your own charts.
Here is sample Sankey chart made using SankeyMatic: