The Burndown Chart report provides an estimation statistic pulldown, which allows you to display a burndown with a different estimation statistic from the one set in the board configuration. We configure our boards with Story Points as the estimation statistic, so that we can track velocity sprint over sprint, but we have the option of displaying a different burndown by choosing a custom field as the estimation statistic on the Burndown Chart. This helps us track progress within the sprint. Adding this functionality to the gadget would allow us to display it on a wallboard, which would help to make this valuable information more visible.