The googlechart component provides basic charting capabilities. It currently supports a single chart type; to render a collection as a pie chart:

All that is required is for the object to implement the (horribly named) PieChartable:

package org.starobjects.wicket.view.googlecharts.applib;

public interface PieChartable {

  double getPieChartValue();
  String getPieChartLabel();
}

The label is used to point to each sector on the pie chart, the value determines the size of each sector relative to the other sectors.