The Pie Chart already allows the end user to rotate the chart and move slices. It would be very nice if the end user could manipulate the chart in more ways.
For instance, using the context menu of the chart to switch from 2D to 3D, or from vertical bar to horizontal bar. It would also be nice if the end user could change the properties of individual series.
My generalized question is to provide more context menu's that provide the end-user with the ability to change the chart.