An archivist at the Schenectady Museum and Suits-Bueche Planetarium in New York state was curious about some vaguely-labeled film canisters in the basement. The films inside had been recorded on a pallophotophone and, oddly, there aren't any more around on which to play the recordings. He managed to get two engineers interested in figuring them out. One of them managed to build -- from scratch, over two years -- a working pallophotophone.
That by itself is extremely cool. What is even cooler is that when they listened to them, they heard a speech delivered by Thomas Edison. It was broadcast live in 1929 when Edison was 82 years old, he shared the stage with President Hoover and Henry Ford, and you can listen to it here. There were other gems as well, but the fact that we can hear Edison's voice over 80 years later makes me feel like a time-traveler.
(cross-posted at Quodlibeta)