This kind of homemade USB plug could also be used for other things, like repairing USB cables.
Step 1: Supplies
A Soldering Iron
150-200 Grit Sandpaper
Blue LED (Other colors will work just fine, too)
Small Piece of Perfboard
I used a 1k resistor because I just wanted a nice looking light, not a blinding one. ;P Feel free to use a different value if you choose.