Over the years, there has always been some sort of cluster development or another going on. At the moment, we are experimenting with Instant-Grid.Above: a stack of relativly fast pentium 4 nodes.
Above: the master node under the table and its monitor.
Below: a close-up of the master running Instant-Grid.
Before experimenting with Instant-Grid, we used a custom build of Parallelknoppix. When using it, at least three big/notable povray rendering clusters were made (probably more which I can't remember.) But Instant-Grid has a lot more features, and although its documentation is half in German, it is remerkably easy to use.