Team Visifire will show you how to create Drilldown Silverlight charts using Visifire.
In this sample application, chart can be drilled down till 2 levels. The default chart would show yearly sales of a fictitious company for the period 2006-2008. On click of column representing the sales for an year, monthly sales for that year is shown up. Further it can be drilled down to find product wise sales for the selected month.