Besides GWC, here is what I listen to…
Art & Story
This American Life
On The Page
NPR - Wait, Wait, Don’t Tell Me
Sci-fi Surplus
NPR - Movies
NPR - Technology
Buzz Out Loud
CNet - Car Tech
The Real Deal
F1 Minute
The Speed Report Video Cast
Autoline Detroit
World Wide Automotive Report
KCRW’s The Business
KCRW’s The Treatment
Filmspotting
BSG Official Podcast with Ron Moore
NPR - It’s All Politics
NPR- Story Corps
KCBS - Phil Matier
KCBS - John Madden
The Skeptics Guide to the Universe
NPR - Science Friday
Web Comics Weekly
Sam and Jim Goto Hollywood
Creative Screenwriting Magazine
NPR - Car Guys
Money Girl
Grammar Girl
Naive London Girl (Very mature content that is hard to believe sometimes)
Savage Love (Mature advice show)
This Week in Tech
Trigger Street - videocast
That is all off the top of my head. My job (which is ending at the end of the month) allows me to listen to podcasts most of the day which has been great.
From the above podcasts, I would say just about anyone should check out This American Life and The Skeptics Guide to the Universe. Those two podcasts are well done and should appeal to just about anyone. Most of the other podcasts are very niche oriented podcasts. The Real Deal may be useful to anyone seeking practical advice and info on tech topics. Each episode covers one or two topics in depth.