Yesterday, Susyn Stenvaag kindly invited me over to see some amazing work on giantess avatars. I am embarrassed to say that I don't know whether this is new; clearly I've not been keeping up.
I should say that the photos here show stationary figures, but I believe them to use the same constructs as are used for the giantess avatars--I met someone using the avatar to amazing effect. (Hi, J4ne!)
In particular, we visited the Giantess Avatar Shop... here's a photo I took later on:
The boots are sold separately. Note in particular the array of faces one can choose from. That's been an issue with giant avatars--you'd like to be unique, and the face is the main way we recognize individuals. (Of course, one always wants more; I'd love to be able to hand over my head slider settings and get a customized head that is me.) The faces are even better than this 2-D photo would indicate. If you go to the shop and walk around, you can see them in three dimensions.
One of the issues with avatar shapes built up from prims is joints. I think that the unadorned mannequin in the poster shows improvement... though of course the modest clothing and standing pose hides and minimizes joint issues.
Thank you, Susyn, and thank you to the lovely people I met for the first time.
UPDATE: Read the comments--you owe it to yourself to check out the image of Aliasi Stonebender's impressive work!
UPDATE #2: Definitely check out Ms. Stonebender's latest comment, and the images linked to. You'll be amazed, as I was.