I bought a couple of these little USB 2.0 hubs for £1 each in PoundWorld intending to adapt them to be powered hubs for use with RaspberryPi computers. Alan here (http://pihub.blogspot.co.uk/2012/06/raspberry-pi-power-supply-and-powered.html) beat me to it, but I wanted to give it a go with a flying power socket. As usual, heat-shrink sleeve comes in to save the day.
I didn't like the original USB lead and plug so I bought a USB-to-Micro USB cable (again for £1) and cut it in half. One end goes to power the RPi and the other is the input USB.
The input USB has only 3 connections made, the red power wire is cut short and ignored. I did connect the ground (GND) wire though because the purist in me doesn't like the idea of floating grounds (blame my MSc). The output for power to the RPi via the micro USB plug only has the GND and +5v connections made and the other 2 signal lines were chopped short and ignored.
The power input was made from a DC power socket salvaged from an old lead for a dead PDA and with some black heat-shrink it looks quite professional and hard-wearing. I have a small hoard of 5v 2A power supplies that were for various long-deceased gear and one of these is powering all this.
And it works like a dream!