While browsing today, I found this interesting website for medical renders. This is stuff like you see in medical documentaries that give a peek into the human body (blood vessels and such) using 3D renders. A great example is "Inside the Human Body" and this episode about the ear, which is very impressive!
Molecular Movies features tutorials and inspiration if you're into medical renders! They're primarily in Maya, but I'm sure you can translate it to whatever program you're using.
Check it out here: