To shine your appliances, rub them with rubbing alcohol.
To remove a bathtub ring, let warm water sit in the tub with vinegar (approx. 1 cup) in it. Wipe away with a damp sponge.
Either a baking soda paste or rubbing alcohol will remove permanent marker and crayon marks on walls/floors. Test a spot first to make sure it works with your finish!
Vinegar water will counteract pet urine smells.
If you sprinkle your carpets with baking soda prior to vacuuming, it will draw out odors.
Sprinkle baking soda in kitty litter pans after filling with fresh litter to prevent your stinky kitty from stinking up the whole house when she's done.
WD40 prevents soap scum from sticking to your shower doors. Wipe a thin film over the doors after cleaning.