I'm a big fan of the various podcasts on the 5by5 network. These span a variety of topics and subjects, almost all of which I'm interested in. A subset of these shows are recorded while being streamed live. You can listen to them via the 5by5 website.
I do this for all my favorite shows, but I soon found that I didn't like having to play them within the browser. So I wrote a Mac menubar application that monitors the feed status and starts playing my favorite shows whenever they start. I've been using it myself for months, then decided to share it with other 5by5 fans. It's called FiveLive. Enjoy.
What is new in this release:
Added support for the new Notification Center in Mountain Lion. You can now optionally have notifications appear when shows go live. Configure the appearance and functionality of these notifications in System Preferences > Notifications.