Way back when, when John Conway's game of life was first introduced in Scientific American's Mathematical Recreations column, it was introduced with a challenge. Conway suggested that it was impossible to have a bounded initial set of live cells which would grow without bound. After much mucking about on computer time which was expensive in the early 1970s, a group of Honeywell developed the glider gun, which is a large-ish collection of a few dozen live cells which spits out a glider every so often. This satisfied the ``finite initial size'' and unboundedness criteria, since (with sufficient memory and time), the seed of a glider gun could send out an arbitrary number of gliders (which wouldn't hit anything, and so wouldn't die). Conway coughed up the bounty, I think, which amounted to about $50 U.S.