Re: What to do. There is lots.
TomD
"I'd be tempted to buy one to play with if I could begin to imagine a use for it."
Industry has embraced CNC in order to make repetitive parts with machined accuracy, but most of us don't need accurate parts to the level of interchangeability, or multiples. And where either are concerned there are often other less expensive routes to those goals.
Makers are a new addition to the scene. Making is distributed industrialization, in a world with file sharing, and open source. So if you look at that Maslow CNC piece. He made some perfectly awful chairs (plywood is the wrong structure for several of the described load paths; waste is huge; they don't look comfortable), worse than IKEA, but he made them himself.
So for myself the main thing is I design or draft in CAD. This is pretty easy, you could learn to draw circles squares and lines, in a few minutes. Then you basically learn how to index parts to each other, and when necessary copy or adapt existing forms. If you went through typing and then word processing, you know the enormous power of the computer to adjust formatting, spelling, send out mass mailings, adjust the look, create a file of formats you can cut and paste, and be electronically communicated. Similar tools exist in CAD, that make it pointless to waste time on designs or drawing outside of CAD. Once a design is in the system, it can be adjusted for size, or the components reused.
The frustration is having digital patterns and then needing to copy them out and go after them with normal woodworking tools, that will do a worse job. Another major frustration is all the machines and tools one may buy to do jobs that a single CNC would do. Of if you know how to do CNC, there are simple machines that can be created to do a single job cheaply and accurately. like a Domino, or screw threading. But that is getting pretty advanced.
CNC is awesome at curves. boats and guitars are two things I design in CAD, and hate to have to plot out by hand. One thing it does very well is branding. With things like boats and guitars, it's sad, but having script on the project enhances the value. CNC makes that kind of thing easy. For instance a simple router can engrave very detailed pictures or script onto a grain of rice. Imagine the logo or marking one could put on the endgrain of planes.
I do leatherwork and would like to be able to cut out parts, and mark cuts for the tooling. At this point, I make the design, print it on paper, or clear film, then cut out a ply pattern, and if that survives I make a lexan one if the product comes into my catalog. With CNC I could go directly from concept to cutting it out with a dragknife. I don't need to store patterns, and if the shop burns down, I won't have lost all my patterns. That same knife can make custom boxes to post your products in, and transfers, stencils, or large stamps to brand the boxes.
Sometimes a product won't fit a machine, but you may still be able to make the jigs that will allow the product to be made, using your other tools.
The enhanced process doesn't need to affect the hand work or craftsmanship that goes into your work, in a commercial setting it tends to drive products that will be series production. For me it would probably be the means to making custom go more quickly and deeply into the process, and to add artistic touches and branding.