I have two magnets implanted in my fingertips, which let me 'see' electromagnetic fields. AMA!
6 months ago, I got two neodymium magnets implanted in the ring and index fingers of my left hand. They allow me to pick up other magnets and small metal objects (up to the weight of about a bottle cap). But more importantly, they sit in the middle of one of the body’s densest clusters of touch-sensing nerves. When my fingers enter a magnetic field, the magnets inside move and I am able to sense this as a vibration of varying frequency and intensity. In effect, I have a 6th sense – the ability to feel magnetism!
There was a great AMA from a different guy with these a little over a year ago, and I figure it's been long enough that not many people have seen that.
Some more pictures:
A picture of the magnet before it went in: http://i.imgur.com/Ni9889L.jpg
Getting them implanted (WARNING: A BIT OF BLOOD): http://imgur.com/a/NOtQs#TktbCWs
1 week later when I took out the stitches: http://imgur.com/a/NOtQs#eQSKaUZ
2 months later, all healed up: http://imgur.com/a/NOtQs#0eYpFHv
Edit: Thanks guys for all the interest and questions. If you're just seeing this, read through and someone probably has already asked the questions you were wondering about. But I do hate it when people abandon their AMAs, so I'll check back in a few days to answer any stragglers.