Quote from IronFist:
If you want to trade futures you can use openecry's demo for 2 weeks for free with realtime data and you can even use another better charting program like SierraChart (which also has a free trial period).
If you want to trade Forex you can get a free lifetime demo account with oanda but you're limited to their Java platform (and they're not an ECN) but you can get a feel for stuff.
Dunno about stocks.