Hello i have used and adapted fortran algorithm for computing contour layout.
see http://www.crm.umontreal.ca/Galerie/ContourPlotApplet_Eng.html for original project.
i have reworked it and created a dataset and a Renderer for JFreeChart.
you have full sources in jar file and you can launch the jar file to see an example.
(you must have jcommon-1.0.14.jar jfreechart-1.0.11.jar in the same dir)
i added two screenshot for those who don't want to download launch the test application.
The code is very, very low on comment for the part that does the computation.
All in all it seems to work correctly and provide a nice alternative to scatter plot for large data.
Any comments is welcome.