Probably one of the most useful $10 gifts you can give someone, ZipWraps from Digital Innovations (the skipDR. disc repair people) is a little puck packed with a spring-loaded mechanism that smoothly lets you extend and retract your headphone cables.
Setup requires nothing more than popping open the case, looping your cable around a hook inside, closing the cover and pushing a button to engage the spring. Then just pull the cord out to the length you want and when you’re done, hit the button to wind them in again.
It’s available in black and white versions and has a clip on the outside for attaching to your pants or bag or whatever so the thing doesn’t just dangle while it’s in use.
ZipWraps Automatic Earphone Retractor [product site]