David Griffeath's Primordial
Soup Kitchen A wonderfully eclectic site including soup recipes, CA postcards and links to many CA programs, including Griffeath's own WinCA, which is one of the few discrete CA simulators that lets you use large neighborhoods.
Mirek Wójtowicz's MJCell - This is absolutely the world's best Java-based Cellular Automata simulator; runs on all machines. Mirek also has a standalone Windows version of the program called MCell.
