A big box of random phone, computer, and audio cords all tangled together is the worst. Not only is it impossible to find what you need, but the cords get all tied together in knots, and this useless box of cords takes up room on your shelf. I've come up with a great way to organize cords, which I've been using for the last ten years.
Start by organizing your cords by type, and get as specific as you need to based on the size of your collection.
Next, coil your cords up and do something to keep them coiled. I have three examples shown below.
Whatever you do, don't use tape. After tape sits on your cord for a while, the residue will get stuck to the cord and make your cord sticky.
Next, find yourself an extra piece of trim or something similar that's about the size of a yardstick. For my example, I used a cheap piece of foam-core primed white trim that was left over from some project or another. Now cut this material into several 8" lengths, and put a hole through the middle of them. Don't worry about the exact lengths, and don't worry about the exact size of the hole; something close to 1/4" should be good.
Now grab a few of your old RJ-11 (phone) cords that you have way too many of and will probably never use again, and cut that cord into various lengths to use as hangers for your sticks. Feed one end of the cord through your stick with a hole in it, and tie a knot on the end to keep this cord from pulling through the hole.
Now slip all of your cords onto your cord hanger.
Now hang all of your cords onto a bunch of hangers on the wall, which can consist of a bunch of screws or nails, or a piece of pegboard if you want to get super-fancy. Really long cords get their own hanger. That's it, that's all.