Reposting the observations I've made on GTSCity:
1)
Werewolves have a transformation animation. Depending on how this works, it
might be possible to edit it to create smooth growth. Barring that, if it's a static transformation, someone could make an animation for such a mod.
2)
Mammoths shake the ground when they walk. If this isn't hardcoded (like how radroaches were the only mob you could stomp on as an attack in Fallout 3) it could be possible to give this attribute to a giantess mob. It could even be possible to make a script that would give the attribute to your character when she exceeds a certain height threshold and then remove it if she shrinks back. Combine this with a passive fear effect that doesn't make neutral mobs go hostile and we could have a really immersive, playable GTS mod.
I've had one growth mod idea so far: a mod that increases the size of a female PC whenever a dragon soul is absorbed. It's possible that I could even reuse scripting from my
Attack of the 50 Foot Woman mod, though it'd obviously have to get a new title to better fit thematically.
An idea posted by FreshSalmon is to make a shout that will grow your PC temporarily. This might be tricky depending on how shouts work, especially if we can't add more shouts. Assuming we can, we'd then have to find a way to inject that shout into the game world.
As far as getting greater than 10x scales is concerned, we'll probably have to wait for the script extender mod for that. With no CS, there is no telling when that will come out.
Thankfully, Skyrim seems to be a little bit smarter about scales and collision this time around. Big characters will still clip through objects if they are pathed to walk under them when normal sized, but the infamous bug where giants would fall a short distance and die, that cropped up in Fallout 3, seems to be gone.