I'd want a pen or pencil to come out of my fingertip. Retractable, of course. I'm always looking for something to write with and never can find anything that works decently.
I know this is not a thread where one says a superpower and the other a side effect. But how about: "the pencil which comes out of your finger break very often, and to sharpen it you have to spin your whole body 360 degrees a couple of time" , just like a normal pencil sharpener.