Here's a story from Russia that suggests that stamps from Russia have been created with the smell of fruits. Also mentions another stamp from Switzerland that smelled of chocolate. Further, the UK issued a stamp in 1996 that smelled of eucalyptus. It also reports that in 1999 Brazil opted for a stamp that smelled of burnt wood to raise awareness for forest fire prevention:
http://www.sptimes.ru/index.php?act...ory_id=10834I don't have examples of any of these stamps, but it would be interesting to know just how long the smell lingers, as one would expect that the aroma would diminish over time.