I am surprised to be recommending Senator Chuck Schumer's Positively American and yet it is a very powerful and effective book.
Schumer is a liberal and very positive Democrat but he is also very smart and has some profound insights into contemporary American thinking.
For any Republican who would like to understand what happened in 2006, the Schumer explanation is compelling and sobering. He and Rahm Emmanuel have understood that a hard left Democratic Party will never be a majority. They were prepared to recruit candidates who were electable and to accept that those candidates would infuriate their more liberal wing. They saw a center-left majority as preferable to a happy leftwing minority. It is a formidable warning about how they will run 2008 and beyond.
Makes me want to buy it.
Update: Comments for that post on Freakonomics has a link to Donald Rumsfeld's Flickr account,