Some of the best interactive exchanges can usually be heard on the radio, and most certainly on the open-line show. Audience participation on radio programs began as far back as the 1930s Back then, it was the studio audience that participated rather than the caller. The open-line show can be painful to listen to if the callers are lacking. It can be a little less painful now that we've got emails and texts that have been added to the talk show. It seems to work better on radio than it does on Television.
The first time I heard a radio program take advantage of the Internet was back in the early-to-mid 1990s. It was Mitch Garber's open line sports show on CIQC. He started to invite emails and would set up a live chat session on IRC where listeners could "gather" during his show. Today radio shows and the Internet go hand-in-hand, but back then, it seemed like something very innovative was starting to happen. No doubt a lot of old-school broadcasters must have resisted, but there was no looking back.
In the United States, radio is far more political and ideological than it is up here. Our talk "stars" have far less influence than the Limbaughs and Becks do with their syndicated talk shows. Many of them have TV shows too. Needless to say, these programs keep their followers' attention 24 hours a day through their web sites, blogs and tweets.
You would be hard-pressed to listen to any radio program today anywhere, be it powerhouse or community station, without instantaneously being presented with web-related information about the program. In many cases, through the wonder of streaming and podcasts, programs are even attracting new listeners through the Internet rather than through the airwaves.