One possible solution to the shortage of affordable urban housing comes in a portable, delivery-ready package. Actually, two: one for the first floor, another for the second. So claims Bob Carrane, CEO of Affordable Housing, in Chicago, which sells factory-built, modular homes for inner-city neighborhoods. Carrane's 1,200-square-foot, three-bedroom homes start at $55,000, or about one-third the average price of a single-family house in Chicago. Marketed through nonprofits, churches, and housing developers, the manufactured homes can be assembled on a vacant city lot in as little as one day.

-- Anne Murphy