I use halflings as a number of different species, each a different culture of the same biological species, from Leprechauns to Domovoi the maurauding mongol hunlings.I'm sure it's obvious from recent posts that I completely agree. For one thing, I think hobbit-like halflings are a fine idea in Tolkien's specific vision, but don't fit high adventure or swords & sorcery. For another, I see no need to fully stat out multiple races or creatures that are mostly identical, especially when most of the differences are cultural.
And if I were creating a fae area, I would want lots of little folk races, most of which are simply bizarre cultural variants of Pixie, Nixie, Gnome and Leprechaun. In Irish folklore, there's something called a Clurichaun which is identical to the Leprechaun, except that Leprechauns are always found making one shoe, while Clurichauns are always drunk and surly. The Fear Dearg is also practically identical, but prone to gruesome practical jokes and prefers to dress in red. I feel that in a fairy-tale-inspired adventure, every element should be potentially confusing, so practically every creature should be unpredictably different from others that are superficially similar.