I know IB has a good simulator but they require an account and that costs $100/year minimum (they don't pay interest on anything under $10k, the bastards). Google Finance would suffice except they don't even allow me to short a stock. Ideally I'd like a simulation program that lets me place in fake stops and profit targets, short and buy stocks, and even more ideally other commodities, but I'm most concerned with shorting stocks. And I don't want to shell out green.
Try investopedia there simulation games and also you can make your own game and select shorted stocks. I know because I shorted RIMM a month ago but I will wait ( no money involved)