ThinkOrSwim
ThinkOrSwim is an investment brokerage - for more details please visit their website at www.thinkorswim.com
In order to use ThinkOrSwim as a source of streaming live (or delayed) market data you will need to have a ThinkOrSwim trading account.
The main requirement for using ThinkOrSwim as your source of streaming live (or delayed) market data is to have their client software ("thinkDesktop" not the web-based interface) running on your computer (and in the same Virtual Machine if running ONE on a Mac). Please note that you must be logged into the client software