This Mapplet will create pie charts on Google Maps from text files formatted as comma separated values (CSV). The CSV data must have a header row, geographic latitude and longitude columns to point to the locations to place the charts on. The charts created can be clicked on to show the values. The charts can also be dragged and moved to a different location on the map if necessary.
If you want to take this for a spin, click on this link http://dominoc925-pages.appspot.com/mapplets/piechart.html.