I ran across this app a couple of weeks back and have just started playing.  This is pretty cool.  I've been able to adapt the line chart to work with one of our dbs and generate line charts based on categorized data.  Pretty slick.

The charts need to have the X Axis modified so lots of data can fit but the download provided here includes no information about playing with the charts.

I believe that the charting code comes from fusionCharts.com: http://www.fusioncharts.com/goodies/fusioncharts-free/

My thanks to the chef for providing several examples for integrating the fusionCharts files into a Notes db.  If I get anything clever working, I'll post it back here.