What exchanges are supported by the various data services / data feeds that Investor/RT supports? I'm specifically looking for the ASX (Australian Stock Exchange) on a realtime basis?

eSignal supports the Australian Stock Exchange and Indices on a realtime basis. To find out more about the Real-Time Exchanges and Administration Fees for eSignal, search their knowledge base here.

You can access the DTN.IQ Symbol Guide by clicking here. It doesn't appear that they currently support ASX (7/29/4).