If you do a lot of ADO.NET Data Services development, you might find yourself opening the services over different ports to host multiple services from a single machine, especially if you aren't just hosting it over IIS.

This is a classic case where you'll probably want to see what is already running on your computer. For this and many other cases, the TCPView utility is invaluable.

In short, this is another great SysInternal tool; just run this command from any console window, or even the Start | Run window.

\\live.sysinternals.com\tools\tcpview

Enjoy!