Nothing is more refreshing on a hot summer day than a cold glass of homemade limeade. Next time you mix up a batch, leave time for the rinds to soak in some sugar first. You'll end up with a much better, more flavorful drink.
Image from Vicky Wasik.
After you've squeezed the juice for your limeade, cut the leftover limes into quarters or eighths to expose more of their surface area to the sugar. Mix the lime rinds with half their weight in sugar (weight allows for the correct ratio despite fluctuations in lime size) and let them sit for at least two hours. During this time, the oils in rind will be drawn out, which results in a stronger citrus flavour for your limeade.
Once your limes have had a chance to react with the sugar, pour some of the juice plus water over the limes and strain to collect all the sugary, citrusy liquid. You'll end up with a strong limeade, so you may want to dilute it with water (or alcohol!) before serving. This technique works for lemonade, too.
How to Make the Most Flavorful Limeade, Summer's Best Drink [Serious Eats]