Based on this post, I just finished doing this today with a power supply I had at home out of a computer in a closet collecting dust. It works, and is dead simple to do! An absolutely great way to save money rather than going out and buying a power supply from Radio Shack or somewhere else (that will set you back more money, for sure).

Since I didn't need all the various combination of voltages and was fine with the power supply being off if there was no load on it (e.g. a charger or some other device hooked up to it), I did what the guy did in the embedded video at the page above. I didn't put any fancy "posts" on the PS, didn't incorporate another switch or LED (the existing switch will work fine), etc. The only things coming out of the back of the case are four black wires (ground), four red wires (5v), and four yellow wires (12v). Each same-color grouping of four is then soldered to one alligator clip (so three clips in total).

Because of this approach, I had to do zero modifications to the power supply case at all, and I just used the various gear I already had lying around. So, in total, $0 spent. That's a price I can get behind (and perhaps more important, the Wife Acceptance Factor is very very high ).