I've been putting this off too long, here's a transformation that deserves some attention and that I can't find a huge amount of (although I'm sure there's loads about). Twinning (in the definition I understand) is the process of one woman replicating herself either through the transformation of another into a copy of herself or through the splitting of herself into multiple parts (sometimes resulting in size change or splitting into 'attributes', eg. the teen titans go! episode set in raven's head or the Immonen run on hellcat). I've found a few different examples of it, but of course I want MOAR! :P
Here's the few that I've found so far:
http://cluedog.deviantart.com/art/Na...Acluedog&qo=77
http://cluedog.deviantart.com/art/Th...cluedog&qo=240
http://www.process-productions.com/f...ht=slumberland
I know the second one's not strictly twinning, but it's still an awesome sequence, check cluedog's pages for the other two parts of it.