I've played Humans, Half-Elves (usually Aquatic), Elves (usually Aquatic), a Half-Orc and some Gnomes. Never played a Dwarf or a Halfling, I don't think. (I played a Dwarf in Warhammer Quest, 'though.)
I've played more Daelkyr Half-Bloods and Gnomish Giant Space Werehamsters than Halflings...