Actually, I have an RFID tag implanted in my hand, and I was rather worried that it would blow up or something when I would put my hand on our stove. Turns out it's no problem at all, I have tried everything possible to get a tag to explode, break, get warm or even just stop working, but I haven't been able to find a way.
Mostly for the body hack value of it, at this moment I only use it to log on to my computer. There's a book out there ('RFID toys') that describes how it could be used to unlock/start a car or unlock a door. Maybe if I ever have a spare weekend or two (heh) I'll make something like a 'hidden' safe, a seemingly normal wall that springs open when I wave my hand past it. Maybe put a gun safe in there or something. If I ever build another house for myself I will try to put some hidden areas like that in it.
Overall and right now it's of limited practical value. Still makes for a cool story and discussion starter on transhumanism.
Very difficult to do - the induction element won't start until a significant (pan-sized) amount of ferrous material is very close to the cooktop, and shuts off the moment it's lifted away - there isn't enough room to get your wrist in there - and it's doubtful that your watch by itself, even if it was made of iron, would be enough to trigger the sensors on the element and let the element turn on..
Safety features and all that - they thought of that already.
It's just as if you'd have your hand hover over a normal hot plate when messing around at the stove. Things get warmer gradually, you notice it at once, and you pull your hand away.