Under a banner that proclaims that "evolution is natural as gravity!", Darwin@Home is an open source software project that aims to bring the process of evolution to your home computer. From the initial efforts to evolve locomotion, the project now encompasses a broader framework for evolution in general.
Darwin@Home is the latest in a series of initiatives within the field of Artificial Life that have produced compelling videos of in silico "lifeforms" that have evolved complex behaviours through natural selection. You just have to take a look at the project's eye-catching and though-provoking video:
And if you like that, you will also enjoy these other celebrations/illustrations of computer-based evolution in action that I found on YouTube: