Outer suburban nieghborhood homes may have negative values now that gasoline and commodity prices have accelerated. Suburbs are inefficient, and really only exist in the US. Earth to builders, stop making more homes.
The builder's inventories of land and unsold homes are probably worth closer to zero than what's on their balance sheets, such that book values are much much lower than many suspect. Additionally, revenues should be hard to come by for every percent of loss the dollar suffers vs commodities, which makes "exurban" homes values closer and closer to zero or negative. Earth to citizens, move back into cities, and plow those homes 100 miles away from your job back into farms.