With the recent release of 
iTunes 4.9, I am discovering the world of 
podcasting.  Podcasting is essentially on-demand radio.
I enjoy listening to talk radio on my hour-long commute to work, but nearly all the programs available nowadays focus on politics.  I would rather listen to programs on computing issues, science, and other areas of interest to me.  I was stuck suffering through the garbage large media conglomerates were willing to jam down my ear canal, until now.