Besides smelling amazing (and packing a superfood-level dose of vitamin C), lemons might be some of the most useful fruits around, adding flavor to nearly any dish and keeping pretty much everything else in the kitchen (like avocados, potatoes, and pears) from turning brown. Just sprinkle some lemon juice in fresh guacamole or on fresh-cut fruit, and the citric acid will help slow oxidation (the cause of that nasty brown film that covers the surface of cut or bruised fruit surfaces).
While it’s certainly no replacement for the real deal, lemon juice can also serve as a last-minute stand-in when that deodorant stick comes up empty. Apply lemon juice directly to those stinky spots for a quick solution. It might not last a whole 12 hours, but the powerful juice will help keep offensive odors at bay, at least until it's easy to slip out to the store (or get through that first-date dinner).
Another less obvious use for these yellow wonders? The citric acid in lemons can act as a natural insect repellent. Spray lemon juice around doors and cracks where ants are entering the house to keep them at bay. Washing floors with a lemon juice/warm water mixture can also help repel roaches and fleas, and hanging dried lemon peels in the closet can keep away moths.
Finally, celebrate the spring (or add some sun to winter) by lightening hair with this natural highlighter. After shampooing, wash hair with a 1:3 ratio of lemon juice to water and let dry in the sun. Repeat daily for a few days and see natural highlights magically appear! (Okay, so maybe it's not really magic.)