A good idea for a small bathroom, under hanging shelves for things like cotton balls, cotton swabs, etc. Also great in the kitchen, for a spice rack over the stove. Just hang jars from bottom of the cabinet.
Stretch a rubber band over your gallon of paint to swipe the extra paint off of your brush. (If I manage to do this without spilling the entire gallon of paint getting the rubberband on, it's truly a genius idea.