XAML Spy is the visual runtime inspector for Silverlight, WPF, Windows Phone and Windows 8 Store applications which provides direct access to UI visual tree, runtime UI modifications to check/set different properties temporarily, monitor events, extract package contents and much more.
With the release of XAML Spy version 2, the company introduced a light weight Free version for the XAML designers/developers to play with their XAML files. Read more to grab your copy.