Well... a whole other approach is to work on really good procedural skins with masking to provide for area variation. I did not to bad creating procedural skin, lips and eyes... BagginsBill has done procedural lashes and eyebrows I believe... add masking to that to deal with the texture differences such as palms, soles of feet, knuckles, knees, buttocks, nose and eye sockets etc and you would be able to do tremendous character differentiation without textures. Procedurals don't have to be quite as complex in the fancy optical effects as BB's... I was able to do procedurals that focussed on conventional diffuse, specular and displacement using just some of the fancy fresnel etc. demonstrated by Face_off. Moles, blemishes and all sorts of individual characteristics could be done procedurally through shader mixing. Really I have never understood the Poser obsession in some parts on "untouched" non-postworked renders based on entirely Photoshop photo-captured textures... it is easy to do a likeness of Marylin Monroe on a single sided square with a good texture but if the ideal is true CGI then why should the texture be photo-based instead of precedural?