Under the iTunes model of digital music, a single song is the new album. It’s not much different from what they were doing with radio hits before, but nowadays a hit doesn’t have to have a whole album behind it. At this moment, half of the top ten selling songs on iTunes are singles. You could picture one day having a slow-release model: pay $10 now and we’ll send you a new Green Day song every month for the next year. After the year, the 12 songs are grouped together into an album. Green Day can spread the hype about their music across the whole year and gradually add new material to their set list to keep the show exciting. CDs never provided a convenient way to do this.