Logical progression for PAX was build some kind of UI around it. I thought of writing my UI but then I realized the building a UI for assembly parts and letting people look at the code inside it is not a small task and there is already a tool for it i.e. .Net Reflector. There is even nice Add-in model that lets you extend reflector functionality. Here are few things I found that were helpful for me to create this add-in.
This is add-in is pretty simple. It adds a menu item to File menu. Open Xap menu launches a OpenFileDialog that lets user pick a Xap file that they would like to see.
When user picks the file, it opens the xap in tree view structure. User can then expand them to see individual files inside it.
User can click on some of the files to see the content. E.g. for Xaml File text is shown. For image, image is shown and for Media files, media is played.
Here is the source code for the project.