Using GA's to solve the Magic Square Problem
http://www.wi.leidenuniv.nl/~gusz/Flying_Circus/3.Demos/Java/MagicSquare/index.html

Curve Fitting Using GA's
http://www.wi.leidenuniv.nl/~gusz/Flying_Circus/3.Demos/Java/GA_Simulation/index.html

Text Matching using GA's
http://www.wi.leidenuniv.nl/~gusz/Flying_Circus/3.Demos/Windows/Match/index.html

Generalized Curve Fitting (scroll to bottom of the page to retrieve Demo)
http://www.sdi-inc.com/e.html
 

Adaptive Systems / Cellular Automata

Brookings Institute's Sugarscape
http://www.brook.edu/sugarscape/default.htm

Swarm - Modeling Artificial Life
http://www.swarm.org/

Avida
http://dllab.caltech.edu/avida/

Boids by Craig Reynolds
http://www.red3d.com/cwr/boids/

Darwin's Pond
http://www.ventrella.com/Darwin/darwin.html

Tutorial on Emergence & Game of Life
http://lcs.www.media.mit.edu/groups/el/projects/emergence/index.html

Game of Life - try the glider, exploder, etc, or create your own lifeforms
http://www.bitstorm.org/gameoflife

Irreducible Semi-Autonomous Adaptive Combat
http://www.cna.org/isaac/

Capow - a program which combines CA with virtual reality
http://www.mathcs.sjsu.edu/capow/intro.html

CAffeine- a collection of Java CA applets
http://psoup.math.wisc.edu/java/java.html