Two years ago, Nas named his eighth album Hip-Hop Is Dead. And, based on the genre’s plummeting sales over the last few years, that seemed all but true. Then along came the New Orleans rapper Lil Wayne, with his distinctive flow, raspy Southern drawl, and radio-friendly beats. His sixth solo studio CD, Tha Carter III, debuted at the top of the charts in June with sales of more than a million. It was the first time an album of any genre had sold that many copies in a single week since 2005, proving that while hip-hop, like all music, may be hurting, it’s not lifeless. It just needed the healing touch of a superstar.