Where to find a real-time database of stock prices/info across different exchanges?

I'm writing a program that compares different many stock exchanges (AMEX, NASDAQ, NSX, ADF, EDGAR, ISE, PHLX, BATS...) on a specific stock (say, Apple). Is there a single place that I can find all of this information in a way I can easily access via my program? Or if not, where can I find these separately?