Beware: you can bruise your feet with high heels.
This happens to me so infrequently that I forget about it every time, but during some circumstances -- like jumping around on a stage at the Holiday Inn during Guelph Pride -- I manage to damage my feet in an incredibly painful way.
It feels like a constant burning inside the ball of my foot, which becomes a sharp pain each time I take a step. Since my foot doesn't actually swell up or anything when this happens, I assume that the bruising is of some tissue deep inside...a muscle or a joint or something.
The last time this happened was when I tried to break in a pair of very high feather mules. The deceptive thing about this is that the pain doesn't actually start until a few hours later, so you've got no warning that something's wrong until it's time to recover. And that takes days of hobbling around and inspecting your foot for gangrene.
So be careful, girls...feet will only take so much.