Probably everyone knows the standard trick for determining in one pass whether a stream admits an element occuring more than half the time. But what not everyone might now is the origin of this method.
Stuart Shieber writes about the algorithm (discovered by Boyer and Moore) and the mishaps it had on the way to publication. The article also describes how the followup paper by Misra and Gries came into being. Interestingly, I almost always see the Misra-Gries generalization being cited, and not the original Boyer-Moore method.
(HT Fernando Pereira)