Take a simple USB cable, I used a A-B type cord. Clip off one end, if using a A-B cord, clip off the B end. Strip off the main insulation and the inner insulation on the black and red wires. You now have a 5v 100mA DC power supply that will work in any powered USB port.
Step 2: Get Lights
Now, take a string of X-Mas lights. You want to cut off the plugs, but on the male plug end, leave some wire on it, this can be used a plug for any AC application. You need to seperate all the lights. Any bulb holder that has three wires running into it can be thrown away, these are special holders used to wire up the string. you may keep the bulbs though, as replacements. Also, you can save the extra two wires that run along the string, they can be used for circuits. When done you should have a pile of christmas lights and a pile of wire
Step 3: Let there be light
Now, take a christmas light and strip off some insulation from both wires Connect those wires to the exposed wire on the USB cable, and plug in the USB cable. Then find something from your desk to mount the light in/on. I used a piece of foam from an IC and a Bawls bottle.