I have altered the heights of the races in my game so that there is more diversity in body size. All I did was change the height entry in the cration kit for each race. However, when I play the game, my viewpoint is not from the actor's new, modified height. For instance, I made the argonians taller than Nords. When I see an argonian standing next to a nord in the game, I can see that the argonian is, indeed taller. However, when I play as an argonian, nords look down at me when I am in first person view. When I zoom out to 3rd person view, I see that the camera is centered on the torso of the character rather than the head. How do I fix this so that the camera is at the height of the character's head?

You can check this mod http://skyrim.nexusmods.com/mods/22182 and see how he did it, there is even a tutorial there.
But from the description, it seems you can only have it for one race at a time, because it's the same skeleton for all.

You must make the new skeleton.nif so that they fit the new heights.