Under the category of "should have been there in the first place" here's what you can do to your Miata's center console in one afternoon with little to no money depending on junk bin.
This article is just a brief show-and-tell of how I did my NB console but without precise hole sizes, electrical splice m and so on because you'll have to decide that depending on your what junk you have lying around. I haven't worked on an NA center console much so this may or may not apply exactly to you but it might.
The first thing is to add power. This is useful for charging cell phones and iPuds inside your center console. In my case, my stereo can directly connect to an iPud but I don't want it sitting out in the open hence, I want to connect to it inside the storage cubby.
Obviously you need to yank your console and work on the bench and also because you'll have to run power and ground wires to its location while it's out. A good place to tap for power is the nearby cigarette lighter wiring plug.
Splice a pair of wires (power and ground) from the lighter and run them toward the back of the center console area with a little extra length and add female spade clips. The rest of the work you'll do with the console on the workbench.
The only place I found on the console to mount a cigarette lighter was at the very back of the cubby. I used an old Miata lighter socket but Walmart and Autozone sell aftermarket ones, some with lighted rings if you want. There is a very close tolerance between the lighter socket and the frame of the car but it can be done. The higher up you mount it, the better.
I like the stock Miata socket because it contains a built-in fusible link that'll blow if you screw something up and also because the spade connectors are easy to identify: big-positive, small-negative. If you do it right, the plastic ring locks the socket to the plastic. The rubber cap is just something else I had but not necessary.
I used a 1" hole bit which turned out to be a millionth of an inch too big, leaving my socket a bit wobbly. So, drill small and route or file it larger until your socket fits in snugly. I used JB Weld to make mine solid as hell so I'm good now.
Nevermind what I'm holding, it's just a little plug for right-hand-drive Miatas.
Now that the socket is in, you'll have to bend the electrical tabs flat in order that it doesn't hit the frame of the car. To repeat, if you drill the hole higher up, you'll have even more clearance which might be necessary if you use a longer, aftermarket socket from Autzone. The Miata's is pretty short.
If all you want is power, you're done! Just put it back in the car and connect it to the power/ground wires you ran and attached the female clips to.
Now you can use a double USB charger to keep multiple iJunk charging at the same time!