Strange Universe is a triangular cellular automaton. It is run in iterations in which the state of every cell on the board (on or off) is determined by the number of neighbors it has on or off in the previous iteration. The rules can be adjusted to the user's liking but the most interesting rules can be loaded with presaved zoos of interesting patterns that I discovered.
There has been some debate as to whether or not triangular cellular automata have enough diversity and complexity to yield interesting patterns. I had even heard that no gliders exist in triangular cellular automata. Well, I found a rule set that does have a glider (a shape that drifts across the board without leaving a trail behind it). This glider has eight frames in it and even "looks" like it is flapping wings or swishing a fish-like tail when it is gliding. I think it is a very beautiful pattern. You can see it in this picture.
I have also found a rule set with an interesting growth pattern. From small seeds (called acorns in cellular automata), it grows into a near perfectly circular shape with increasing complexity within the circle as the circle gets larger. This picture shows the pattern after a couple iterations.
Strange Universe is freeware and will run on any Macintosh computer.