My first post here... but here's my fairly sizable list, heh:
The Adam Carolla Podcast
Ask A Ninja
BlizzCast
The Bugle
The Bungie Studio Podcast
CAGcast
CO-OP
Diggnation
Digital Flotsam
Downloadable Content, the Penny Arcade Podcast
Drunken Gamers Radio
Penny Arcade/PVP DND Podcast
East Meets West
The /Filmcast
Gamers With Jobs
The Gamespy Debriefings
gdgt weekly
The Geekbox
Giant Bombcast
Idle Thumbs
iFanboy (audio+video versions)
The Instance
KCRW's Good Food
A Life Well Wasted
Mondo Movie
No Agenda
NPR: Car Talk
NPR: Fresh Air
NPR: Planet Money Podcast
NPR: Wait Wait... Don't Tell Me!
Out of the Game
The Phileas Club
PlatinumGames PGTV
The Phileas Club
Player One Podcast
Rebel FM
Security Now!
SModcast
Systm
tech5
Tekzilla
This American Life
This Week In Tech
Three Moves Ahead
Top Secret: The Bionic Commando Podcast
The Totally Rad Show
Windows Weekly
Radiolab
ListenUP
Retronauts
1UP's Sports Anomaly
Of those that are un/under-represented in this thread, I would recommend the following:
The Bugle (
http://www.timesonline.co.uk/tol/news/world/us_and_americas/us_elections/the_bugle/): Scripted weekly comedic take on the news, a la Daily Show(but totally British), with Andy Zaltzman and John Oliver(from Daily Show fame). Easily one of my favourite podcasts.
The Phileas Club (
http://frenchspin.com/en/site/phileas/): A solid monthly world/politics discussion with guests from across the globe giving their views on each of the topics.
WNYC's Radiolab (
http://www.radiolab.org): If you're a fan of Robert Ashley's ALWW, this is the true inspiration for it, not TAL. This show finds a way to blow my mind every single episode. They take interesting topics and break them down, make them easy to understand and follow, and then package it all with great voiceover/music/cutting to make it endlessly entertaining.