Digital Evolution

Have you heard of the names [URL=http://www.his.atr.jp/~ray/tierra/]Tierra[/URL], [URL=http://dllab.caltech.edu/avida/]Avida[/URL] or [URL=http://www.greythumb.org/twiki/bin/view/GreyThumb/Nanopond]Nanopond[/URL]? If you are an evolutionary biologist (or...