Another kind of polymorphism that's way underappreciated is what Qt calls "static polymorphism" (http://doc.qt.digia.com/qq/qq13-apis.html#staticpolymorphism).

This is just a fancy word for naming stuff consistently instead of trying to shoehorn constructs to have some kind of formal language-aware relationship via abstract methods, overloaded methods, etc., which sometimes just increases coupling/complexity with no real benefit.