The good thing about the work on a photography studio is all the cameras you have to play with. I asked a friend to take a few pictures of her face with our 39 megapixels Hasselblad H3D, so that I'd have some nice high-res images to use as skin texture, make brush alphas, etc..
I put a few of those images together on a zip file for you guys to download. I had to save them as .jpg files (each .psd have around 100mb), but I'm pretty shure it hasn't lost it's definition.
I also put together a preview of the images, so you can see what it's about. The images are around 6400x4800 pixels, except for a few ones I had to crop.
Link -> http://rapidshare.com/files/241976106/photos.rar
Hope it can be useful!!