Rachel and Miles X-Plain the X-Men
I can't second this enough. If you ever had even a passing interest in the X-Men, but never knew where to start, this one is right up your street. They recently did an episode about my favorite mutant, Legion, and it was everything I could have ever wanted.
I'll also toss out Spektromodule, which is Warren Ellis' semi-regular ambient music podcast. DECOMPRESSED by Kieron Gillen, where he interviews comic creators about a specific work that they have done. FOT Matt Fraction is on two episodes discussing the Marvel Method of scripting and an issue of his highly underrated Defenders run. This one his also semi-regular, but has at least a dozen episodes to pour over for a bit.
The Canon is also really great. It is Devin Faraci from Badass Digest and Amy Nicholson from the LA Weekly and they discuss certain movies and if they should be included in the Canon of films. Much like On Cinema. Also, just in keeping with the movie theme, I really, really love The Badass Digest Podcast (aka the Badass Digest Padcast Podcast), which is basically the Best Show of movies. Evan Saathoff and Phil Noble, Jr, two writers for Badass Digest, talk about a major release of the week and then go on tangents about other movies that they happened to watch during the week. Sometimes they have running themes, like last month was Dad Movies, which included the Taken movies, A Walk Among the Tombstones, and the remake of the Equalizer.