I have a new obsession and its name is the Masterworks Broadway podcast.
On this site you’ll find hours and hours of amazing insightful looks into the creation of the Broadway shows you know and love.
The podcasts are organized into series covering individual shows (Chicago, South Pacific, Avenue Q), individual artists (Sondheim, Jerry Herman, Duncan Sheik), and broader categories (Legends of Broadway).
You can get them all here for free. They also have iTunes, zune, and rss links from the same page.
Legal Note: Theatrefolk is not responsible if you spend an entire day listening to these instead of doing whatever it is that you were supposed to be doing.