Amazon has cable runners that stick to the back of a desk for fairly cheap depending on the size you want. So I got a runner that sticks via some strong tape to my desk and it's long enough and deep enough for the cords for two monitors, my keyboard and external drive. I did use two clips on some usb cords I have plugged in back there to keep them from being floppy, but the cable runner was way cheaper I thought (and easier) than messing with figuring out cable length and the right kind of ties.