Chemistry in its Element - a weekly podcast from the Royal Society of Chemistry offering an engagingly-narrated stroll through the periodic table, element by element.
Two 20th century additions to the comparatively small body of concertos for double bass and orchestra: Einojuhani Rautavaara's Angel Of Dusk (II, III), from 1980, and the 1948 concerto of Eduard Tubin (II, III). Those are courtesy of YouTube, but if you're not sated you can hear still more from bassist Phillip Serna, and a great deal more, from the fine Contrabass Conversations podcast.
Darker Projects has a bunch of original audio dramas in the sci-fi, horror, and suspense vein. Think of it as your local community audio-only theatre, or not-actually-old-timey old-time radio. [more inside]
Symmetry. Shakespeare. Islamic medicine. Creative writing challenges. Four podcast series from University of Warwick.
Astronomy Media Player - a generous collection of astronomy podcasts all gathered in one spot.