Good point, duh!! Many trading platforms have real-time charts with them - Ninja, Open ECry, etc. That's probably the easiest way to get real-time charting, assuming you plan to trade as well.
If you have an account at Interactive Brokers that's entitled for ES data, you could use QuoteTrader's free trading and charting software to display ES price/volume.
Alternatively, videos demonstrating QuoteTrader's free charting and trading features, setup and registration procedures, etc., are available for viewing at your convenience: http://www.youtube.com/view_play_list?p=273E65C191D0A761
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