Some of my favorites have been mentioned (Savage Love, CBC Ideas, Comedy Death Ray, Doug Benson, The Max Fun stuff..) but some haven't
-Ideas: How to Think About Science: http://www.cbc.ca/ideas/features/science/index.html
It's a finished run but there's like 20 great shows there
-Ask Mr. Biggs!: http://askmrbiggs.com/
If you like AM talk radio you'll get a kick out of this one. It reminds me of being back in the USA listening to the radio on road trips.
-Common Sense and Hardcore History from Dan Carlin: http://www.dancarlin.com/
The history shows might be the best produced podcast out there. I can listen to them again and again. Common Sense is political, but I like his opinions about getting rid of the 2-party system and the failure of the government.
-C-SPAN After Words: http://www.c-span.org/podcasts.aspx
This one can either be great or boring as hell. Sometimes the interviewer is too busy pimping their own books or opinions. The one about "Hunting Eichmann" was great. Gotta be picky with it.
-The April Winchell Show: http://www.aprilwinchell.com/show-archives/
She use to have a show on KFI in LA for a few years around 2001, then she'd do guest spots on the Mr. KABC show till he got his show pulled. It's a collection of ranting about shopping in LA, Fabio spottings, penis stories, calls from LA porn directors, lots of stuff about the gay community in LA, Hollywood gossip... I don't know how to explain it. I loved it when I was listening live 9 years ago and it's even good today. She was one of the best things about weekend hosts on AM radio it was kind of disorganized but fun and goofy and you'll not see a show like her's again. She'd be a great guest for the new live 7SD shows, BTW (It's not a podcast per-se, but if you use something like the DownThemAll! extension for Firefox you can grab a bunch at one time.)