So, there’s actually a few addons for showing media views.

I wrote a proof of concept “watch me bring your machine to its knees” view, here:

http://addons.songbirdnest.com/extensions/detail/170

The trick is to NOT make a kazillion playlist elements like I do, each one will eat a thread and lots of RAM. Other than that, XUL is pretty easy, it’s essentially just like working with XHTML.