"random number" generators
Pseudo Random Number Generators
Algorithms which create a series of numbers having the qualities of randomness, but are deterministic. Not truely random, but maybe could be used in combination with true random numbers as seed values to increase the generation rate.
Linear feedback shift register (usually hardware implemented, can't find a decent link)
The repeated application of simple rules to array cells containing values from a finite set can result in emerged behavior over time. Cellular Automata demonstrates this and provides interesting possibilities for randomness from complexity.