Medical Science and Human Anatomy Interactives

http://www.thevisualmd.com/interactives_library

Note to Parents:  Be aware that this is a medical site not intended for K-12 learners, but that might be of use to them. It has photos of human bodies and diseases on it, so preview this and decide if your students can handle these  appropriate medical images of unclothed men and women. There are some fantastic resources like an interactive view of the difference between adult and infant skin, and of fetal development. Just pre-view the site before you send your kids exploring.

http://www.nlm.nih.gov/medlineplus/tutorial.html

Note: This site also includes medical information about many disorders, diseases, and procedures. This site is geared toward patients and doesn't include photos, but it does include drawings of human anatomy. Preview this site as well. REALLY good information.