Just read about this before heading out to my office. But, it looked interesting, so I wanted to mention...

BlogTalkRadio

It labels itself as a Social Radio Broadcast Network and describes itself this way: BlogTalkRadio is the social radio network that allows users to connect quickly and directly with their audience. Using an ordinary telephone and computer hosts can create free, live, call-in talk shows with unlimited participants that are automatically archived and made available as podcasts. No software download is required. Listeners can subscribe to shows via RSS into iTunes and other feed readers. Our network has produced tens of thousands of episodes since it launched in August of 2006.