SModcast and S.I.R. (SModcast Internet Radio)
I listen to almost everything on the network. A bit of explanation about the network might be helpful.
SModcast is now operated like a radio station. Plus One Per Diem and Jay and Silent Bob Get Jobs are daily shows that air from 8am to noon west coast time. Having Sex with Katie Morgan is daily at 9pm west cost time. You can listen live on the website.
After the daily live shows are done they play random shows from the entire library through the player on the website. The rest of the shows are weekly. There's 1 or 2 new shows each day.
You can go to the page for each show, including the daily ones, and download them as an individual podcasts.
It's really best to start from the beginning, although for the original podcast, SModcast, you might want to jump to episode 3 or 4.
My top three favorites of the network are SModcast, Tell 'em Steve Dave, and Hollywood Babble-On.
Eric and Kathy
This is a podcast that's the best bits of a morning radio show in Chicago. It's not for everyone but I like it. Might help that I've been listening for years so some of the conversations are extra funny to me with the added knowledge. Still good starting fresh though.
Start as far back as you can and go from there.
How Stuff Works
Science, tech, general knowledge podcasts about a range of subjects. I think there's a RSS feed for each show but I just get them through the Zune network. There's also an app to access all of their shows from your smartphone.