Neo, www.iitm.com
Has a free trial game that you can download. It comes up with random prices (up or down), plugs them into the simulation, and keeps a running total of your fake "assets". Also graphs the assets so you can see if your winning or loosing. I think the random prices average out to zero over a large sample so that your success or failure are dependent only on your money management skills. IE- Position size taken on each trade.