Read this story. It is another great explanation of the housing collapse, this time from the perspective of people who made money on it (they saw the house of cards and shorted some of the riskiest transactions).
I hope the next time we ramp up, and things look really good, smart people like this do exactly what they were doing...examining the underlying assumptions while those who made profits simply made profits. Most importantly though, I hope someone listens to these guys.
Hat tip to Thairish for putting me onto this article.