The BioDigital Human beta is an online application that allows you to explore human anatomy. You can zoom and rotate the model as well as turn anatomical systems on and off. In the above screen capture the skeletal, digestive, respiratory and cardiovascular systems have been turned on. You can also drill down into the systems to see details of them.
Along with systems you can look at common conditions. That list is rather short, and I am assuming it will grow as they add to it.