Hearing Jerry Jeff Walker's "Mr Bojangles" on the radio, preceded by the interview with Uncle Charlie and his dog Teddy - the segue between the two made me go out and buy the album that afternoon. Didn't know who wrote it, didn't know who did it, didn't know the title, had to sing it to the guy at the music store.
I agree with one of the preceeding people about Ellen McIlwanie's slide guitar.
Siegal-Schwall Band (live, at the Quiet Knight) doing their unusual "low-energy" version of "Corrina". You think Taj Mahal is relaxed, listen to Corky Siegal, Jim Schwall, Rollo Radford and Shelley Plotkin do it.
Interviews with the old folks, segueing into "Old Friends" - Simon & Garfunkel of course, on the album of the same name.
I'm sure there are many more.