NASA has an amazing list of podcasts. Some of this content is in HD and all of it is informative or amazing. I was born only a year after man landed on the moon. My fascination with the space program only grew through the development and lifespan of the shuttle program. I find all things space to be interesting, and some of these podcasts cover the very newest and cutting edge of what NASA is working on.
This collection of podcasts allows you to pick and choose from your favorite missions, audio vs. video and frequency. I confess that I have chosen a video only, HD version where possible and most missions. These podcasts do not come at alarming rate.
The production quality of most is pretty high, with special note are the ones from JPL and the Chandra team. The selection offers some that are geared for kids while others are pretty "educational" and rich in material covered.
If you have any interest in space, the technology of space missions, astronomy or just keeping track of general NASA activity, this site is a fantastic resource for your podcast selections in the NASA catalouge.