Which Duplo bricks have practical uses in System building? Traditional 2x4 and 2x2 Duplo bricks can be used to bulk out models and provide a structural support for landscapes, but have there been any other uses for Duplo bricks of all shapes and sizes in System scale MOC's?

I can find two examples, one of a Duplo barrel being used for a water tower and another that uses a Duplo crown to form the pinnacle of a structure.
Check out these links:


this MOC uses a Duplo Ladybug Base.
this modern classic uses a Duplo piece as a major element.