This screen shot shows Apple Inc.'s new music-discovery feature, Ping, a potentially useful addition to iTunes, letting you see what songs your friends are buying and where your favorite bands are playing next. (AP Photo/Apple Inc.) NO SALES

This screen shot shows Apple Inc.'s new music-discovery feature, Ping, a potentially useful addition to iTunes, letting you see what songs your friends are buying and where your favorite bands are playing next. (AP Photo/Apple Inc.) NO SALES