Google body is an anatomical simulator of the human body. Ok, get your minds out of the gutter. -_^ The skin layer has clothes on it. I swear, some people..
Anyways, I ran across this actually because I saw it in a Verizon commercial of all things, and went to investigate a bit more. It's actually really amazing! You can fade in and out different levels of organs, muscles, bones, etc, and it's actually quite detailed (I think...I'm not exactly an expert on the subject).
Check it out.
http://bodybrowser.googlelabs.com/body.html#
EDIT:
One annoying thing...you can't really focus in on one body part. I was trying to get a better look at the muscle structure in the hand...not that easy when it's always off the the side of the screen. :\