Boids - Craig Reynold's flocking applet
CA - self-replicating & evolving patterns
Caffeine - a collection of Java CA applets
Cafun Simulator - complexity toolkit by André Homeyer
Cellular Automata - incl explanation
Double CA - game of life
GA Playground - toolkit by Ariel Dolan
Interactive Fractals - Alberto Strumia
Isle Ex - Webside CA
Java applets for NN & Alife - fantastic selection
Javalot - NNs, TSP, Lorentz
Java Mountains - with code
Life 3d - Thomas Feldbauer and Markus Doetsch
Lotus Artificial Life - various applets by Tim Tyler
Lsys - LSystem based organo-fractal forms
Mandelbrot - Frode Gill
Morphogenesis - Przemyslaw Prusinkiewicz
Sandpile Model - self-org by Jos Thijssen
Self-Organizing Feature Map - by Simon Lucas
Self-Replicating Worms That Increase Structural Complexity through Gene Transmission - Hiroki Sayama
Self-Reproducing CA Loops - Christopher D Osborn
Simulating Physics using Virtual Atoms - Tim Tyler
The Trend Cellular Automata Programming Environment - Hui-Hsien Chou