There are lots of power wires and data cables inside a desktop computer and they can be an incredible mess.
Keeping the wires and cables organized makes it easier to maintain your computer, improves air flow, and reduces the amount of dust which collects inside your computer.
Current mass storage devices (hard drives, optical media, etc.) use SATA cables, a fairly stiff plastic coated cable with several wires embedded inside. SATA cables come with a warning not to fold the cable too tightly or they can be damaged.
Step 1: After - a neater setup
(This isn't an original idea, a friend showed it to me and many others have done it too.)
Step 2: How to do it
The cable won't stay tightly wound and will easily slip off the end of the tool. Then just bend the ends of the cable as needed to plug the connectors into your computer.