In the tradition of investigative science/humanities radio shows like To The Best Of Our Knowledge and The Infinite Mind, WNYC’s Radiolab centers around a broad subject, like sleep, morality or stress, and glues together interviews and intuitions about it.  While To The Best… and The Inifinite Mind are very structured and strive for authoritativeness, Radiolab is more conversational, kind of like Sound & Spirit, lighter on the scientific details, but no less interesting. I would call it casual philosophy. Seasons are tragically short, but you can find listenable archives on the Web site going as far back as 2005. I caught a clip of Radiolab from an ep of This American Life, and I agree with TAL host Ira Glass that Radiolab should have wider listenership.