I have a little haml I want to test. Is there any XAML fiddle rendering application available?
And yes, I figured it out. This is always my first reaction (for all time).
XamlPad is offline, but it is a very small application that allows you to play with Xaml. This is similar to what you want:
https://msdn.microsoft.com/en-us/library/ms742398(v=vs.90).aspx
XAML Spy also lets you mess with XAML.
http://xamlspy.com/