There are countless stories in which characters sell their souls in exchange for something, but like any commodity, you have to know the value of what you're trading. Why sell your soul for a new car when it's worth as much as a new jet? Wouldn't it be embarrassing to try to sell your soul for the power of flight, only to find out it's worth no more than a few frequent-flyer miles? Now thanks to Soul Compare, a website that uses your Facebook profile to measure your soul in "gigaMorgans," you can find out exactly how much your soul is worth, and get offers to trade it.