Subraces. IMHO, they're more or less min-max bait for some players. Besides, I think that cultural distinctions & what not could be handled just through flavor text, particular skill & feat selections, character names, stat placement, etc. (i.e., stuff that can be easily selected during character creation) rather than building a new race with nifty built-in machanical bonuses.
To a degree, this includes a lot of what I call "A.K.A." monsters, as well--monsters which are basically the same, but different: orcs-hobgoblins-orogs-bugbears (i.e., tough Medium-sized evil humanoids that increase in HD and a few bonuses, for use as grunts against PCs as they level up) are a decent example. Kobolds-goblins-xvarts are another example.
Though I think the large varieties of dragons & giants are kinda neat, I could honestly be fine if there were less of them.
Humanoid-animal combos. There's a fair number of these already in myths, but I do get tired of an overabundance of newer creations that inevitably appear (it does seem like people want to put their own spin on some sort of cat-folk race, wolf-folk race, avian race, reptilian race, etc.).
