While other stamps may use sweet smells in an effort to sell stamps, Brazil's first scented stamp was used to bring awareness to the damages of forest fires. A set of 4 stamps smelling of burnt wood featured an anteater, a flower, leaf, and a burnt tree trunk, each of which indicates what is at risk when a forest burns.
The Brazilian postal authorities also issued a stamp scented with the aroma of coffee. Brazil accounts for much of the world's supply of coffee beans to caffeine junkies everywhere.
The end-product of a different bean was honored by the Swiss -- chocolate. Swiss chocolate is world famous for its smoothness and richness of flavor. The stamp, which came in a foil-wrapped booklet, much like a chocolate bar, only smelled like chocolate; it tasted like plain old stamp glue.
China issued a stamp with the aroma of sweet and sour pork, probably their most widely recognized meal, in celebration of 2007 the Year of the Pig.
What scents would you like to see on USPS stamps?