I think the rind of the red-fleshed pomelo varieties has an almost floral fragrance to it.
There are also several Japanese citrus whose peel has a unique flavor/fragrance. Yuzu, for example, has the aroma of lemon, kaffir lime, a sour bitter tangerine, the fragrant peel of a Satsuma, all combined together along with the subtle but distinct smell of grapefruit (maybe the overall composition of yuzu fragrance is like a quarter grapefruit). Many of these citrus varieties are used in Japanese cooking primarily for the zest from their rind, rather than what is inside.