Beyond architectural applications, CAD is ideal for mechanical parts, product design and visualization, and producing files for CNC (computer numerical control) and 3D printing.
Marine design is a specialty area for which CAD is particularly well suited. Hulls require hydrostatic analysis and precise control of complex curved surfaces.
Rhino3D has a graphical programming tool called "Grasshopper" that generates and manipulates 3D parametric models. This makes it very easy to explore many variations on a design by simply moving "sliders" to change parameters instead of drawing separate CAD models.
In addition, Grasshopper has a general purpose "solver" called Galapagos that randomly (intelligently) modifies a bunch of slider values until an optimal condition is reached. Referred to by its inventor as "Evolutionary Computing", it helps to have a programming background to get the most out of Grasshopper and Galapagos.