Dolly, the world's first animal to be cloned from an adult cell, was put down February 14, 2003, due to a tumor in the lung. Her death has drawn increased attention to how little we really know about the potential health problems associated with genetic cloning. The journal Nature offers a special Web focus on "the life of this extraordinary sheep," including current and archived news articles and scientific papers. These resources offer a great way for readers to delve into this topic at depth and learn about the science behind the news.