Anyway to stop wires from getting tangled up all the time?

My PS2 controllers, and Headphone wires tangle up as much as they can, like they have some infectious disease. What once were 8 ft cords are now 3 ft cords. They just constantly get tangled up in themselves (not with eachother). I can't seem to get them straightened out. If I do get them pretty straightened out, they'll just end up tangled as hell the next day. What can I do to prevent this? Don't say iron them.