As a teenager I could reliably do 'card tricks' - picking out a sequence of four or five cards in order. Also applied it to a party game once, giving the name of the card as well as just 'higher' or 'lower' - you should have seen peoples' faces.

I could describe the sensations I went through, but never did know what was going on. I once did an extensive statistical study to see whether I could affect the random number generator of a calculator as well, but that was only borderline statistically significant. Unfortunately I can't seem to do it any more.