Written in C++, HeeksCNC is an add-on for HeeksCAD. The user can add machining operations.
These can then be output to NC code. The NC code is then shown as red and green lines on the screen.
The NC code is generated using Python script, so it can be configured for different machines.

See some example of HeeksCNC being used here: http://code.google.com/p/heekscnc/wiki/CaseStudies

HeeksCNC uses pycam for the "Zig Zag" operation HeeksCNC uses libarea for the "Pocket
operation HeeksCNC uses libactp for the "Adaptive Roughing" operation