In a comment on my post on The Demise of Oldies on FM radio below, Matt points out that satellite radio is indeed largely free of commercials:

There may be some satellite radio channels with commercials, but mostly the only commercials one hears on satellite radio are promotions for the service’s other channels and specialized programming events. (Rather like the "commercials" one sees on HBO…and for the same reason. Their business model is dependent on being commerical-free as a marketing strategy, and so accepting outside advertising would be just a case of killing the goose.)

I get one of the satellite services on DirecTV, but they cancelled their progressive rock station, and it wasn’t very good anyway–it played mostly jam bands, which are nice but aren’t prog rock. Hence, I don’t listen to any of the stations. However, from the little I’ve heard, there weren’t any commercials other than promos, just as Matt says.

It used to be that one listened to the radio in part to find new songs and artists, but the internet seems much better at that than radio ever was. Recommendations and sound sampless at  and other sellers provide lots of leads, as do email discussion groups, artists’ websites (especially links to other artists’ albums they worked on), and music ‘zines (with links to artists’ sites with sound samples) all provide very efficient ways of finding new music, instead of listening to a lot of stuff you don’t like on the radio in order to find an unexpected gem.