C# - Windows 8 App, creating custom control with Xaml
The following URL shows how to create custom control with Xaml.
http://blogs.msdn.com/b/mim/archive/2013/03/19/create-a-custom-user-control-using-xaml-and-c-for-windows-8.aspx
Another
http://blogs.msdn.com/b/windowsappdev/archive/2012/10/15/building-a-custom-control-using-xaml-and-c.aspx