I like The History Chicks for interesting info on women in history and book recommendations, a few comedy podcasts like Welcome to Nightvale and the Ricky Gervais show (no longer a podcast but you can get it as an audiobook now from Audible.com), Podcastle (fantasy), Pseudopod (horror) and Escape Pod (sci fi) for short stories, and a couple of shows to do with religion like Sunday Night Safran and The Imaginary Friends Show. Oh, and AM, which is just the morning news on ABC radio, but I tend to busy when it's on so I listen to it later in the day via podcast.