To brighten a load of whites, pour in ½ cup of lemon juice into the washer during the wash cycle. The natural bleaching action of the lemon juice will zap the stains and leave the clothes smelling fresh. Then hang the clothes in the sun (cheapest & most effective all-natural whitener) to dry.
Spot-treat a rust/underarm stain– Spray equal parts of lemon juice and water on the stain. Let it sit for a few minutes and then wash as usual.