Yet another excellent online free anatomy and physiology resource:

I especially like the way that this site presents information. For example, the muscular system section has some very helpful features. A toggle function in the middle of the display allows you to smoothly scroll through the layers of tissue in a particular region. A chart on the right of the display contains Origin, Insertion, Action and Innervation information. Clicking on the highlighted Origin/Insertion information will reduce the anatomical diagram to show only those points for the specific muscle. Clicking on the Actions of the muscle will activate a demonstration of the action by a human figure in the display.