I was talking recently with a friend, who is very active in the stock market, about the financial meltdown and the many books that have been published trying to explain what happened. He has read several of them and the two that he recommended most are Quants by Scott Patterson and Fool's Gold by Gillian Tett.
Quants focuses on the financial-math whizzes, who developed the complex trading systems that fueled the run-up in the credit markets. The author is a little over the top in his descriptions of the characters. His explanations, though, of the impact of their actions is very readable and right on.
Fool's Gold is written by a reporter for the Financial Times of London (which in my humble opinion has surpassed the Wall St. Journal in the quality of writing about financial issues). Tett has been writing about derivatives and the credit markets for several years and brings that background into her explanation of the history and aftermath of the debacle.
I encourage you to take a look at both of these. -Henry