I've done an em only podcast (for amusement only) for about 450 episodes. Myself and the EM dungeon on Spooky pinball are the only two currently. The more the merrier.
I've done game overviews, repair info, a lot of technical stuff, interviews with players, restoration experts, collectors and one designer. I talk about bingos, bowlers, arcades, pitch and bats, flipper stuff, flipperless stuff, prewar, you name it.
My passion is really the oral history and technical stuff. Game overviews I do mostly to show the depth and breadth of EM design.
If you do decide to do it, I'd love to hear it.