Data Providers lists a number of website which provide Stock Market Trading Data and dynamic content providers. Data providers normally provide data such as quotes and pricing,announcements and news. These can even include giants like Bloomberg and CNN. The NYSE(New York Stock Exchange) also could be classed as a data provider.
Some of these places also offer stock market content and dynamic content(automatically refreshing on your computer) for a fee usually.
If you are going to get serious about your trading finding some dynamic content providers is the way to go.
These all help you stay informed and ahead of the rest of the market.