Just about every month, housing values in the U.S. fall. That, in turn, increases the number of people who owe more on their houses than they are worth--either trapping them in homes they may no longer want or putting them in danger of financial catastrophe if they lose a job or are otherwise unable to meet the mortgage. Underwater: Options When Your Mortgage Is Upside Down offers valuable advice to homeowners on ways they can unload a house they...