Whether you're at home or stuck in prison, dropping the soap in the shower is something you'll want to avoid altogether. So once again magnets have improved the human condition with this soap holder that ditches the rope.
Now I will admit, it doesn't have quite the same alliteration as "soap on a rope", but this magnetic soap holder is far more aesthetically pleasing. And it won't look like your shower is frequented by lumber jacks.
One section of the holder attaches to the wall, while you simply jam the other into a bar of soap until it sticks. The two are connected via a magnet, and I'm going to go out on a limb here and assume they're made from stainless steel so they don't immediately rust after your first. At $40 it's unfortunately quite a bit more expensive than a short length of rope, but totally worth it for those of us with slippery hands. More here.