AdDuplex is the leading cross promotion network for Windows Phone and Windows Store apps empowering developers to advertise their apps for free by helping each other.
Register at www.adduplex.com to get an AppID for your app and start promoting other apps, they'll promote yours in return.
This extension includes the SDK for Windows 8.1 and Windows Phone 8.1 XAML apps. Not suitable for Windows Phone 8.1 Silverlight apps. Use the WP8 version for Silverlight apps (available via nuget).