Ever wonder how things work inside. Well, okay, I suppose you need to go get an advanced degree in physiology or medicine if you really want to understand how they work.
But if you've ever just wondered what things really look like in there, take a look at this CT scan image.
If you have to get a CT scan or MRI yourself, ask for a copy of the scans on CD. They should be willing to provide it without cost (or hastle). Now pop the CD into your Mac running OS 10.4 and go get a free open source copy of OSIRIX. Instead of a little image like the one here, you'll see it full screen, with all kinds of cool tools to change the density, color, angles, etc.
Ta-dah, all you'd ever want to see of your own insides--and then some.