So let's dance, or at least listen to "Telstar" from the ending of Mad Men, Season 2: Episode 10.*
Named after the Telstar communications satellite, the 1962 instrumental was written and produced by Joe Meek for the English band the Tornados. The track reached No. 1 on the U.S. Billboard Hot 100 in December of that year.
"One of the first sci-fi-influenced pop songs," the record featured either a clavioline or the similar Jennings Clavioline, both keyboard instruments with distinctive electronic sounds. It was recorded in Meek's studio in a small flat above a shop in Holloway Road, North London.
* Incidentally, if you're interested I've been following along by reading Alan Sepinwall's excellent commentaries on the series. Hat tip: Joe T.