The GreenHopper Cumulative Flow Chart Gadget displays a Cumulative Flow Diagram on your JIRA dashboard.
A Cumulative Flow Diagram (CFD) is an area chart that shows work-in-progress for a product, version or sprint. The horizontal x-axis in a CFD indicates time, and the vertical y-axis indicates cards (issues). Each coloured area of the chart equates to a workflow status (i.e. a column on your board).
A CFD can be useful for identifying bottlenecks. If your chart contains an area that is widening vertically over time, the column that equates to the widening area will generally be a bottleneck.