The enormous increase in the cost of oil, and by extension, gasoline, has caused many Americans to change their driving habits.

I would hazard a guess that the tight credit will cause many Americans to change their borrowing/credit card habits. As usual, the people who get you-know-what seem to be the middle class and lower.

The mortgage mess has such a load of complicated features, going back to the mandates. But there was an awful lot of monkey business with the subprime market, aggressive marketing techniques, etc. playing on people's ignorance. "You can buy a house with no money down and be upside-down on your mortgage! Just call 1-800-WEGYPYU!"

IMO, greed, pure and simple, is the biggest bar on this Pareto chart (geeky statistics tool).