I don't have a cleaning cupboard, i am lazy and keep each thing in its own room.
So both bathrooms have squirty bathroom cleaner and a cloth in them - oh, and windex. Both loos have a toilet duck and a toilet brush.
Kitchen has dishwashing powder and washing up liquid, floor cleaner, squirty Ajax stuff for surfaces, stovetop cleaner, oven cleaner.
Laundry has laundry detergent, conditioner, bleach, biotex.
Living area cupboard has wooden floor cleaner, carpet shampoo, baking powder (do I mean soda? For shaking on carpet/smelly chair where cat sleeps before vacuuming), orange furniture oil, duster, cloths.
Cupboard under fishtank in sitting room has various fishtank specific stuff.