I am one of those people that keeps my iPod on nearly all day at work - it just helps me focus on what I am doing and not the chitter chatter around me. In an effort to make sure I never tire of my favorite artists, I usually listen to NPR podcasts, some of which most people aren't interested in (think Car Talk's Call of the Week), and others that everyone seems to love (think All Things Considered and This American Life).
If you're looking to fill your day with a little free entertainment and mental stimulation, check out PodcastAlley, which is a great website that is trying to develop the biggest and best directory of podcasts (podcast directory) available on the Internet. It's one of those fantastic, user-generated communities filled with goodies. For my favorite podcast of all time, just read more
Harry Potter! When you're visiting PodcastAlley don't miss out on Pottercast, the top site for Harry Potter news, which brings all the latest developments in the Harry Potter franchise, entertaining segments featuring discussion, theories, interviews and more. Download the Harry Potter Podcast. Both NPR and PodcastAlley allow users to subscribe directly using your preferred podcasting tool.