IGN has some good podcasts
Sadly, Extra Life Radio
is over, but if you run out of stuff, you can listen to the old episodes.
There's a new Penny Arcade DnD Podcast
I don't know if it's your thing, but Ricky Gervais has all kinds of podcasts. They're pretty funny. Unfortunately, they're released as "audio books" or crap like that, so they cost money on iTunes.