In other words what digital content can radio stations produce that would be worth someone paying for? It certainly won't be a simulcast stream of your terrestrial signal.
Newspapers are wrestling with this issue. For them, this problem is even more acute since moneymaker sections such as the classifieds are a mere shadow of the past. What exactly can they charge for and will enough people be willing to pay for it? I just read an interesting post on how FT (Financial Times) has a pilot program where they allow readers free access nine times each month and after that there is a fee. And while I am not suggesting that idea to be transferred to radio sites; it is an interesting idea. If you want to read more about that story check it out on Fred Wilson's A VC blog.
We must be thinking about what type of entertainment or special service our listeners would find valuable enough to pay for. I've got a list of ideas from ranging ring tones to behind the scenes access. I develop and share these ideas with my clients every day. As CPM's continue to decline, countless music options continue to emerge and stations continue to pare down their presentation to try to take advantage of PPM radio might very well find itself with less and less to sell. Well, as much as always to sell, just not enough customers interested in buying it.