Reverend Jones from the Hacked Gadgets Forum has posted a creative way of making an old wall-wart (plug in power supply) into a useful USB power supply.

“Here is a quick and easy way to make an USB charger/power supply powered by the wall outlet. This can be used to charge/power a PSP, iPod or any other USB device.
First you need to acquire a regulated 5 vdc wallwart rated at 500ma or higher. The one I used is from an IoMega Zip drive. It has a switching regulator with an output of 5vdc @ 1amp.

Other parts needed:

1) 330 ohm 1/4 watt resister
1) 10k ohm 1/4 watt resister
1) 3mm LED (red, green or yellow)
1) USB-A jack, female ”