Many riders like to practice while listening to music on headphones plugged into an iPod or other mp3 player. However, you don't want to leave the cord dangling out in front of you, as it's easy to get it tangled in your bars or other parts of the bike.
One way to manage this problem is to tuck the headphone cord into the top of your shirt...
pull the plug end out of the bottom of your shirt, connect it to your mp3 player, and put the player in your pocket.
From there, you'll be left with a nice, tangle-free situation.
Now go ride!