Here is a video of a circa 1964 Livermore Data Systems "Model A" Acoustic Coupler Modem. Amazing to see a computer peripheral from that era that is still functional! Phreakmonkey's K.C. even gets the modem to download the main page of wikipedia.
Background: This modem was given to me ~1989 by the widow of a retired (IBM?) engineer. Computerhistory.org has a Model B dated 1965, and I've seen a ~1967 Model C written up in a magazine. (Interestingly, incorrectly identified as being only 110 baud.)
Even better than seeing it in a museum, I decide to hook the trusty Model A up and make it talk to something. After some trial and error, I manage to get it to talk to a terminal server at work and use it to connect to a linux box. It's ALIVE! So, 45 years after it's creation, this antique modem gets to send data to and from the modern Internet.
Phreakmonkey has more information on his website: 1964 Livermore Data Systems Model A modem - followup/