I love listening to "actual play" tabletop RPG podcasts. If you look beyond the lack of professionalism, occasionally bad audio, and people talking over each other, real creativity and brilliance can be heard from both players and GMs. It's also a good way to learn about RPGs or campaigns you might not otherwise get to play.
One of the original and still best places to find these podcasts is at http://www.rpgmp3.com/. And the best place to start is the World's Largest Dungeon, the podcast that started it all. Five gamers from England started playing the 3.5e module, World's Largest Dungeon, back in 2004 and decided to record their sessions. They finally finished 3 years and 40 sessions later. This kind of long-form, epic storyline would be impossible in any other but the podcast medium. Listening to these episodes, I really got to know both the players and the characters, vicariously travelling with them on their epic journey.
If you finish WLD, check out anything from the Whartston Hall Gamers, also on the same website. This group of gamers from Manchester, England generate truly funny and classic RPG sessions. As one person stated, they are the "Masterpiece Theatre" of RPGMP3.