The Play on Target crew and guest host target NPCs in the Episode 31 of the podcast, where they talk about what makes them interesting and meaningful. During it, they talk about such games and settings as Dune, the Forgotten Realms, Legend of the Five Rings, and of course Dungeons & Dragons. NPCs are one of the more challenging elements for any GM to facilitate in a game, and hearing from other GMs about how they run their characters is often a good way to learn new ways to do it. The guest on the show is a player, and brings a player perspective to the topic.
Background notes on the episode can also be found online at the Age of Ravens blog.