Gadjo Dilo has raised some interesting questions about ethnically specific foodstuffs re marmite (memorably described by Bill Bryson as 'an edible lubricant'). This set me thinking about some of those weird and wonderful edibles/smokables/unguents that only appeal to people of certain ethnicities or long residence in a particular country.
For example, my return trips to Blighty from the Malay Archipelago always involve packing large quantities of the following: cartons of clove-flavoured kretek cigarettes; kacang mete, which are garlic-roast cashews fit for deities; kopi luwak, which is coffee that has been passed through a civet (seriously); and ting-ting jahe, which are fiercely hot and very chewy ginger sweets. I now have regular 'customers' for all these. Tiger balm used to be a must but is now widely available in the UK.
Marmite, of course, is a major component of British diplomatic bags; and I have known Americans in Asia dedicate much time and effort to tracking down 'peanut butter and jelly'. Though quite why, I have no idea.
What's de rigeur for other countries?