AutoCAD MEP - AutoCAD MEP software helps you draft, design, and document building systems.
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.
AutoCAD Arch - Design and document more efficiently with the AutoCAD Architecture toolset, created specifically for architects.
Mach3 - Mach3 is very popular among the Hobby CNC community.
AutoCAD Plant 3D - AutoCAD Plant 3D is a BIM software that lets you create, modify, and manage schematic piping and instrumentation diagrams.
PyCAM - PyCAM is a toolpath generator for 3-axis CNC machining.