perldiver

Go watch a man's finger NOT get cut off by a table saw.

This guy designed a safety feature for table saws:  the blade has an electrical conductivity sensor in it.  Wood = not conductive, so it cuts.  Meat = conductive, so it isn't cut.  More specifically, the blade--you know, the one that's spinning at ~5000 rpm?--stops within 1/1,000 of a second. 

To demonstrate, they put a hot dog on top of a board and ran it through the blade (i.e., the hot dog is representing the thumb of a clueless operator).  Board is cut, dog is not.  Then, for the true show, the inventor put his own finger in the blade on high speed camera.  You seriously need to watch this...my jaw was literally dropping at the end.

This.  THIS is why I love technology and have faith in humanity sometimes.