When I was a kid, bands were touring to promote their newest album. This is not the case anymore and concert prices which were kept below their market rate to help sell records, as Alan Kruger from Princeton mentionned, are now set toward maximizing concert revenue. As an example, the U2 Vertigo tour, Billboard Boxscore reported, grossed US$ 260 million and drew more than three million people to sold out concert. Average ticket sales in the US was US$ 96.92, between 6 to 7 times more than what is charged for a CD. In addition, on its web site, U2 is now proposing a U2.com subscription for US$ 40/year (US$ 32/year if renewal) and has built a U2 store.
Faced with the appearance of illegal download of music for free, the rock groups have adapted themselves and are diversifying their sources of revenues. I have not still yet found if this metaphor is going to apply to the software industry.