I tried learning piano, but it turns out my left and right hand don't like doing different things at the same time (which is pretty wierd for someone who's ambidextrous, but it was a real struggle). Ballet, on the other hand, I would have loved. I taught myself a little of it when I was about twelve and got really obsessed with it for a while, but it was too late to start then if I was going to do it properly (you have to get into pointe shoes when you're around ten).