 <p>Famous <a href="http://www.bitstorm.org/gameoflife/" rel="nofollow">Game of Life</a> seems to be a good idea. Cells are persistence units, JSF, web beans + ejb to display the working area, scheduled beans - to put it in motion. Game's logic can be implemented in EJB or JMS (or even both). You could extend original logic, introduce new objects or rules and finally get Nobel prize for achievements in social modeling :)</p>