English: Simulation of many identical atoms undergoing radioactive decay, starting with either four atoms (left) or 400 atoms (right). The number at the top indicates how many half-lives have elapsed. Note the law of large numbers: With more atoms, the overall decay is less random. (Photo credit: Wikipedia)
You can try and influence a hardware random number generator using a radioactive source with your mind. Results seem to indicate a slight effect although exact conclusions are debated.
A long document about PK from 1987: http://www.fourmilab.ch/rpkp/strange.html