Open the Windows Phone Emulator, launch Internet Explorer and type localhost:
This means that you can have a WCF service sitting in localhost on your desktop and access it directly in code or configuration file via localhost without having to jump through hoops to access the desktop IIS via IP address. In fact, you don’t have to configure networking at all. it just works.
You can also run XNA games in the Windows Phone emulator as well with great performance because the emulator takes advantage of the desktop GPU to help match the performance you will see when running on physical device.
If you have a multi-touch monitor, you can use it with the Windows Phone emulator to simulate touch on a device.