I've been fascinated by wintergreen ever since I read this passage in Farmer Boy by Laura Ingalls Wilder.
Later on, they'd collect the glossy wintergreen leaves and cram them into a jar, filling it with whisky. The liquid would be then be used as wintergreen flavoring, for cakes and cookies.
Wintergreen and berries. Source: Wikipedia
Historically, it's been used as a topical medicine, to treat joint pain, fevers, headaches, and other symptoms. When the wintergreen oil was rubbed into the skin, it provided an immediate cooling sensation.
The main ingredient in oil of wintergreen is methyl salicylate. Which I made in high school organic chemistry class! It was so fun. First, you take some methanol (wood alcohol--ooh, I made that in eighth grade. Set it on fire, too!) and add it to crushed aspirin tablets (acetyl salicylic acid) and then add some sulfuric acid. You cook it a while, and then...
Are you with me? Yes? No?
Well, it was fun, I tell you. At the end of it all, you get methyl salicylate. It smelled so good! Want to try? (DON'T do this at home. But DO suggest to your organic chemistry teacher that this be your next lab project when you study esters. Here's the method on making it in orgo class. Esters are THE funnest part of organic chemistry. Almost as fun as making nylon. Try making the Juicy Fruit ester! Isoamyl acetate, I love you. Okay, I'll shut up now.)
Methyl salicylate, like aspirin, can be poisonous in high doses. One single teaspoon (5ml) of methyl salicylate is the equivalent of 23 tablets of aspirin! People, particularly children, have overdosed and died from rubbing too much of a methyl salicylate muscle-pain relief cream into their bodies.
Apparently, oil of wintergreen is really useful for rust removal and degreasing machinery. Good to know, sort of.
And, the best of all, wintergreen is triboluminescent, which means it lights up when crushed. Remember this party trick? Take a Wint-o-green Lifesaver, go into the bathroom, turn out the light, and aggressively chew the Lifesaver with your mouth open (messy and not attractive. Good thing the lights are out.) And this is what you'll see: