GIMP - GIMP is a multiplatform photo manipulation tool.
Mastercam - Mastercam's Dynamic Milling is a game changer for us.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Carveco - Carveco™ software is the trusted CAD modelling and CNC machining solution to a wide vatiety of industries worldwide.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
Mach3 - Mach3 is very popular among the Hobby CNC community.