A little book, more like a pamphlet, called When ol' blue eyes was a red, which was a valiant attempt to save Sinatra from his older, Reagan embracing, 'That's Dr Sinatra, you little bimbo' right-wing image, and make a case for him being a subversive leftie in his youth. It's not a very good case. He was a pretty good guy in his youth; he made several prominent stands against racism long before the civil rights movement was really big, and it's well documented that he was a generous, liberal guy who gave generously to some left causes. Betsy Blair, Gene Kelly's first wife, who was very left wing, enough that she was blacklisted, described him as a 'good democrat', and that's alway been my impression of him too. This book tries to stretch it out into something more and doesn't really succeed. 
Rednecks and bluenecks, a book about the politics of country music, was very interesting: it starts with the reception that the Dixie Chicks got in the US when they made a joke about George Bush, and then interviews a whole lot of country musicians about their politics. It paints a very interesting picture of American society and what seem like great fractures based on moral and political beliefs, and made me want to track down quite a lot of coutry music (i only really know the older, schmaltzy stuff).