I've started writing some open-source foam cutting software.
http://www.homecnc.org/index.php/FCut
The frontend is fairly complete. The features are fairly minimal as yet. Consider it early alpha.
The backend is currently just a script file that can be run in GMFC as I'm yet to write the parallel port driver.
Anyone wanting to help with development (particularly on an interrupt driven parallel port driver!) is most welcome.