I'm double jointed and flexible. I've been exercising again and I have quite a lot to lose. I was pleased to discover I'm flexible in spite of being fat...
I used to be able to tie a cherry stem with my tongue but I haven't tried that in a long time.
Oh, and I can use my toes like fingers to some degree. I also have an uncanny knack for being able to find things with my feet, especially if they're sharp and pointy. If someone drops something on the floor and can't find it, they'll yell for me to come walk around where they think it might be, and even if it's pitch dark, I somehow manage to step on it right away.
I don't think it's useless, but I have the weird ability (sometimes referred to as super power) to select the best dessert item from a restaurant menu. It never fails - out with friends ordering dessert & offering tastes around, everyone always says I ordered the best thing.
I have the ability to make computer servers go haywire, just by being in close proximity! I don't know of any health issue which causes this. At one place of employment, the head of IT banned me from ever entering the room where the servers were stored. I can also make desktops and laptops go bananas now and then. No idea why.