The final word on the housing bubble?
The Wikipedia entry on the United States Housing Bubble is, I would argue, an example of the site at its finest. The article includes a time-line starting in 1985, and numerous charts and graphs depicting the rise and fall of the bubble. The list of 215 citations at the bottom of the article is a must-read for anyone looking to research this mess. Links to articles like subprime lending and economic bubbles provide more resources.
The article isn't perfect -- it's being constantly updated -- but it's actually incredible that something of this quality has been put together collectively by people who aren't being paid.