Until now I was using the shape of organs, such as a foot, and from the shape imagine the character.
This time I've been doing the other way round. So I create the animal silhouette and use the pattern of the x-rays to decorate or define certain details of the shadow.
We also are close to decide the final design of one of the protagonist, the boy:
Transmedia Storytelling: http://henryjenkins.org/2007/03/transmedia_storytelling_101.html
The Lost thing: http://www.youtube.com/watch?v=cNpxqda8CCM