A colleague in graduate school, where a great deal of paper is consumed, divided people into two classes, bunchers and folders. (I’m a folder, as you might have guessed.)
The impulse to divide human beings into binary categories is very strong—Robert Benchley wrote that there are two classes of people, those who believe that there are two classes of people and those who do not. I’m in the former of Benchley’s classes, and I’ve amused myself during a slack interval thinking of opposites. Introvert/extrovert and liberal/conservative are obvious, but there are many more, though man and woman may not be as strictly defined as was thought in the 1950s. Add some of your own in comments if you feel moved to do so. I’ll get you started.
early risers/night owls
green salsaistas/red salsaistas
judgers/perceivers (if you go in for that Myers-Briggs sorcery)