I never tire of looking at this book. And here is a link to the PBS series Art:21 and the segment on Sally Mann. Have you seen this series? If not, you must! You can watch it right on the PBS website. Here's what it's all about:
“Art:21–Art in the Twenty-First Century” is the only series on television to focus exclusively on contemporary visual art and artists in the United States, and it uses the medium of television to provide an experience of the visual arts that goes far beyond a gallery visit. Fascinating and intimate footage allows the viewer to observe the artists at work, watch their process as they transform inspiration into art, and hear their thoughts as they grapple with the physical and visual challenges of achieving their artistic visions."