What would you consider a good idea for a useless "supernormal" skill or ability?

For example, Douglas Adams’ novel, ”The Long, Dark, Tea-Time of the Soul” features, at one point, a girl who is unaccountably able to rattle off the previous day’s stock prices as they fluctuate – in real time, as it were. While fascinating from the scientific standpoint, the ability is, in itself, of little value.