I admit I don't really "get" body modifications. I don't understand why people would get a tattoo or get anything pierced. I do not subscribe to the notion that they enhance beauty, so what is the point? They are not particularly functional, but then I came across what I can only say is quite possibly the coolest thing I have ever heard of.
It is a body mod that made me "get" it. You can take a very strong rare-earth magnet and implant it in a finger. The neurons in your finger heal and when you encounter a magnetic field the magnet moves in your finger and you feel the field YOU FEEL MAGNETIC FIELDS!! It cannot be over stated how increddibly awesome this is. Ever since E&M kicked my butt up and down Oberlin's campus I have always really wanted to feel the fields that we talked about. That's the thing about E&M for me it is so distant. Newtonian physics is real: you can go out there and feel force, but you can't feel an electric field (correction: you don't want to!)
But if I could feel magnetic fields, wow. Wow! WOW!
I'm not planning on getting this anytime soon. It sounds like there are some problems with it, but it tops my current "what if...?" scenario list.
Here are two articles if you want to learn more:
A body mod online mag (warning a little blood in some of the pictures)