<%= link_to "Condorcet", "http://en.wikipedia.org/wiki/Condorcet_method" %> allows voters to rank candidates in order of preference. If there is a choice whom voters prefer to each other choice when compared to one at a time, that choice will be the winner.
There is a family of Condorcet methods. This method is referred to as "Simple Condorcet" to distinguish it from the Schulze method which is another Condorcet system.