It is not quite often, but sometimes I wish there is an easy way to use various orientations of the coordinate system (e.g. left-/right-handedness and X-/Y-/Z-upness). When making Suica I had to add a coordinate-system-agnostic behaviour, and it was harder than I had expected. It is not just a matter of a different matrix.
Demo 1
Demo 2 with orbit controls
Demo 3 with sizes
Demo 4 with rotations