Some I've been listening to lately:

• Hard Fork - podcast about technology and science from the NYTimes that does a pretty good job of being varied and interesting.
• Search Engine - newer podcast by PJ Vogt from Reply All about understanding weird or poorly understood topics.
• Darknet Diaries - IT security stories, hacking, and red vs blue team defense of infrastructure.
• Behind the Bastards - Stories about terrible people and their effect on society. Start with the Dulles Brothers or Kissinger.
• Mother Country Radicals - Limited series about key members of the Weather Underground during the civil rights era.