I've had pages about cellular automata on my web site on and off for about 3 or 4 years. Of late these pages been offline so the content below is rather old, and maybe out of date. Please bear with me while I update and correct it.

Artificial Life, Cellular Automata & Digital Ants
Artificial life, cellular automata, digital ants? What am I going on about now?
What is artificial life? Well put technically it's the study of emergent behavior in non-liner, dynamic systems. Okay so what is artificial life, I hear you ask. Well a non-technical definition is it's an attempt to create a man made system that emulate the properties that we normally associate with life. Properties like sensing and responding to the environment, reproduction and evolving as the environment changes. It's still a young science so true artificial life has not yet been achieved. But since philosophers, scientists and theologians have been arguing what life is for hundreds of years and there is still no definitive answer, so will it be known when artificial life has been achieved? The simple answer is that we'll know when it happens, in the same way we can tell a living object from a non-living one. But we are still many years from even the most basic artificial life from.
But is this the same as research in to artificial intelligence? Not quite, for two reasons. 1, artificial intelligence seeks to simulate the effect of intelligence, not the actual process. Where as in artificial life the process is every thing, if intelligence arises from this, so much the better. And 2, there are many, many living things which show no sings of intelligence at all, take plants or bacteria.
These attempts at the moment are almost entirely computer simulations, but there are some projects that are attempting to give this life-as-yet-to-bea body.
That is a brief (very!) description of what artificial life is, I'm not going to go in to it any more, this page is about cellular automata, which are tools in artificial life research. If your interested then I can highly recommend Steven Levy's excellent book Artificial Life: The quest for a new creation.
So that's artificial life, but what is a cellular automata. It's a mathematical construct, it has not physical body.The construct has two parts to it One is the universe in which it ’lives’, this is almost always a two dimensional grid of squares, some times this grid is bounded, some times it's infinite in area (remember since it's not real this is no problem). Each of these squares has a state, which
is represented by a number. There must be at less two different states but there can be many more. The second part of the construct is a rule which when applied to one square takes the states of the squares and gives a number, which is the new state of that square. This rule is applied for each of the squares on the grid, or just a few of them depending on the type of automata. Now in the universe
that the automata exist in time, is divided in to discreet steps. Every tick of the clock that runs the universe, the rules take in the state of the surrounding squares and gives out the result, which becomes the new state of that square. Now depending on the type of automata this will be done for all squares or just a few. So you can see that the current state of any given square is dependent on the current state of it’s neighbors. And the neighbors states are dependent on there neighbors, which of course also includes our first square. So you can see that the whole system is riddled with mathematical feedback. Now if you know something about maths, you’l know that this sort of feedback can produce some amazing results. Fractals in general and the Mandelbot set in particular uses mathematical feedback to produce those amazing images.
Even with very simple rules, this interconnectedness of the cells can produce surprisingly complex behavior (take a look at Langtons ant, the simplest possible C.A).
Digital ants is a name I’ve given to one particular class of C.A. A digital ant is a one-dimensional C.A, Chirs Langton called these virtual ants or vants.I’m not sure if any one else uses the name digital ants to describe this type of C.A but I’ll use it on these pages (so there!).
So that’s a basic introduction to both artificial life and cellular automata. For a more techincal (much!) see Alexander Schatten ca page.
For more information on cellular automata and the different classes and types that there are of these constructs, see the page Automata types.
There are quite a few automata pages out there on the web, for details of these see my links and sources page. Quite a few of these pages have automata applets on them so you can see the beasties in action, I've created some applets of my own and you can view them on my automata page (I'm currently bringing most of these up to date with modern java standards so please bare with me for a while)