Some of the ones that I haven't yet seen mentioned:

"Oxide and Friends" is a great interdisciplinary podcast with a lot of focus on hardware and low-level stuff, but always looking at a big picture.

"Array Cast" is a pretty unique podcast about array languages (think APL, J, K and friends).

"Type Theory Forall" - podcast about formal methods and type theory, some absolutely great guests there!

I also have to mention "IPv6 Buzz" and in general "Packet pushers" family of podcasts on networking - listening to it helped me a lot when I had to implement some IPv6 functionality at my job and didn't really know where to start.

Oh, and "Machine learning street talk" is just awesome if you're a bit more philosophically inclined.