This app records your predictions and plots your calibration curve.

Lets say you make 100 predictions with 60% confidence. Once you've determined whether or not they actually came true, then if you are well calibrated, about 60 of them will come true and 40 will not. Make many predictions and discover if you are inherently biased in one direction or another.

It's not all that important what exactly you predict. You don't have to restrict yourself to important events if you don't want to.

If your prediction will influence the likelihood that you do the thing, be sure to enter the probability of the event conditioned on the fact that you predicted it.