Wall St. Journal Reports had a special peak oil episode last year.  Their financial talking heads predicted that exurban real estate would tank.  People would not be able to pay their mortages and their gas bills.  Once a neighborhood reaches the point where 30%-50% of the homes are in default, the bottom drops out of the market.  There are so many properties offered at fire sale rates by the banks that the entire neighborhood's property values plumment.  

One of the financial gurus worried that the government would be pressured into offering another big social program: mortgage bailouts.  

No one actually came out and said it, but implied in their analysis was that Kunstler is right: the suburbs will be the new slums.  

The inner suburbs are developing trendlines that point that way already. Property values going down, child populations going up, it's in progress already.
These exurbs can be mined for scrap and building materials. Once the building boom is over, these same illegals who helped construct them will be back, digging up copper, hauling away utility poles, dismantling the houses themselves. Such huge areas, once even partially abandoned, will be impossible to patrol. I see ghost-towns, not slums.
In response to dima's comment...

I agree, this kind of mining for scrap occurred extensively in Lithuania after the Soviet Union fell apart, and it wouldn't be much of a stretch to see this happening in the exurbs. Occupied houses weren't disturbed too much, but a construction site that was only half-completed, and then abandoned, was fair game. In my wife's village (okay, former collective-farm settlement, to be precise), a building that was set to become a cafe/store was abandoned prior to completion. Within several years, it was looted for its metal fixtures, and its remains were privatized. The buyers broke down the walls, and used the bricks for other structures. The site is now basically a hole in the ground.

Same fate awaited the Soviet military structures that were not immediately put to use by the Lithuanian military.

The really adventurous thieves went after electrical transmission infrastructure.

Quite a few of the electrical wire thieves died, but also triggered enough blackouts to be noticed worldwide in the industry.
They are made from flakeboard, cPVC and PVC pipes, vinyl siding.  There may not be as much worth salvaging from these developments as it might appear.  Copper wire in the houses, scrap wood, and street infrastructure.
I'd say the strandboard, dimensional lumber, wood flooring would be worth scavenging.  Water piping if it is copper, too.  Brick veneer should be easy to chip apart into bricks again.
You might be surprised.  Someone over at PeakOil.com was bragging about how they were using scavenged PVC pipe as fuel for their wood stove.  

I shudder to think of the chemicals released when you burn PVC pipe and treated lumber, but people are not going to be too picky when TSHTF.