Elo
"Elo" is often written in capital letters (ELO), but it is not an acronym. It is the family name of the system's creator, Arpad Elo (1903–1992), a Hungarian-born American physics professor.
http://en.wikipedia.org/wiki/Elo_rating_system
p.s. Careful not to stuble across anything related to electric light orchestra or electronic literature organization :-)
I find myself wondering what "Elo" stands for... anyone?