I drive a lot, and listen to LOTS of books in mp3 format. I was tired of buying new headphones every month just because the cord at the plug end would kink and break the wires inside. I came up with this gadget to limit the range of movement of the cord at this vulnerable point.

Step 1: Find a Mechanical Pen With a Spring.

Open the pen and extract the spring. You can probably throw the rest of the pen away, because it doesn't work without a spring.

Step 2: Applying the Spring: Part 1

Take the spring, and push it crosswise onto the cord, near the plug.

Step 3: Applying the Spring: Part 2

Rotate the ends of the spring around the cord in opposite directions so that more and more of the spring surrounds the cord.

Step 4: Applying the Spring: Part 3

Once the cord is completely inside the spring, work one end of the spring onto the plug housing. Make sure it is snug enough that it won't come off with regular use.

Step 5: Finished!

When you are done, it should look something like this. The spring should keep the cord from getting in a bind at the plug.
This is my first instructable, so comments and criticism are welcome as long as they are constructive.