Computer Aided Design and Computer Aided Manufacturing or Machining – You create the design in CAD and then use CAM software to tell the CNC how to cut the part.
MeshCAM software http://www.grzsoftware.com (Try before you buy with the 30 day free trial)
CNC control and CAM software (Mach3 and LazyCam) http://www.machsupport.com (great software and affordable, limited FREE version available)
CAD/CAM software from http://www.vectric.com (Great designs and user interface, very intuitive, FREE demo)
NCPlot (Allows you to “see” the G-code results before you cut anything – version 1.2 is free! Version 2.3 is awesome) http://www.ncplot.com