Leonardo da Vinci
Artcyclopedia. Marshals many links to museums with Da Vincis, and other relevant resources.
Leonardo: The Secret Life of Mona Lisa, described in French.
"Leonardo da Vinci" by Frank Zöllner (1999). An authoritative 16,000-word biography of Leonardo, with an excellent section on the Mona Lisa.
Amazon. Leonardo Da Vinci by Sherwin B. Nuland. This is one of those excellent new "Penguin Lives," 170 small pages, not one of those horrible door-stops. Dr. Nuland is a surgeon, which gives him an excellent purchase on Da Vinci's anatomical technique. Here's the publisher's blurb.
Reivew by Jonathan Shipley, BookReporter.
"Anatomy takes up a bulk of the short tome, for Nuland is a surgeon and is interested in such things. But what of da Vinci's great artistic abilities? "The Last Supper" and the "Mona Lisa?" What of his engineering feats? What of his interest in mathematics? These are all touched on, certainly, but with Nuland's focus on anatomy, much of what da Vinci is most noted for is only glanced over."
Exhibit: Leonardo da Vinci, Master Draftsman
NPR:Talk of the Nation audio, "Leonardo da Vinci, Master Draftsman" Lengthy multi-topic program, starting with the Carmen C. Bambach, the curator, and proceeding to interview the biographer Sherwin Nuland (January 2003) [42 Minutes]
Official Metropolitan Museum page and gateway (most of the material is under View a special, in-depth feature). See also their "standard" Leonardo page, with some information on the Mona Lisa (at bottom).