Some foods only seem to exist to fill a specific purpose.
Sauerkraut, for example, is something I generally loathe, but it is used in the Reuban sandwich, which tastes delicious, and is pretty much the only justification for its existence that I will accept (regardless of what the Germans seem to think of it, I've heard it's really popular over there).
Figs seem to exist for the sole purpose of making the Fig Newton, a very yummy little cookie that stands out amidst the various candies, jams, spreads, and other recipes I've seen which use them.
Macadamia nuts, while not horrible on their own, are used to perfection in the white chocolate macadamia nut cookie, where the nut provides the perfect balance to the white chocolate, and result in an almost addictive cookie (and if you've never had one, find a place that sells them, they're awesome).
What other such items are out there? What foods, or ingredients, do you think have found their perfect niche, their single ideal use that dwarfs any other potential use?