LinuxCNC (the Enhanced Machine Control) - LinuxCNC: an open source CNC machine controller. It can drive milling machines, lathes, 3d printers, laser cutters, plasma cutters, robot arms, hexapods, and more.
PowerMill - PowerMill is an advanced CAM software that comes with a flexible way to get done with your complex high-speed and five-axis machining processing.
Mach3 - Mach3 is very popular among the Hobby CNC community.
SOLIDWORKS CAM - SOLIDWORKS CAM is an add-in that provides you the leverage of computer-aided manufacturing, allowing you to generate g-code and m-code for CNC machining of different parts.
PyCAM - PyCAM is a toolpath generator for 3-axis CNC machining.
MeshCAM - MeshCAM is the fastest way to generate gcode