I have to agree with Michael on WoW LJ: it would be nice to have a little more variance in the types of races that we choose at character creation. Of course, due to lore reasons, all the trolls we create are Darkspear Trolls, and likewise, all of our Taurens are of the Bloodhoof variety. But it would be nice to have a few more options, especially since we now know that some of the "foreign" tribes and clans might have a member or two interested in joining the Horde.
None of Michael's suggestions would really work -- the Taunka are almost a completely different race, the Forest Trolls can't be very happy that we've killed their leader, and neither the Dark Iron Dwarves or the Iron Dwarves are very friendly to either Horde or Alliance. But there are possible variants out there -- the Zanadalar tribe might have some members interested in joining the Horde, and certainly the Mag'har Orcs are friendly to players. Alliance doesn't have as many options come to mind, though all players are Bronzebeards, I believe, and surely the Stormpikes are Friendly by now.
We've got new hairstyles coming in the next expansion, of course, but it would be nice to vary up the races a little bit, and have even different backgrounds within the race choices. RPers would love it for sure, and even for other players, it would give a little more meaning and power to playing through the various racial areas in the game.