For today’s resources, I listed some free user interface kits for desktop application. Most of them are for OSX. Hope these will help you if you want to make some desktop apps.
Chat UI
Copy Dialog
Email App UI
Minimal Google+
Mini Mountail Lion GUI
Mini Social App
Music Widget UI
Retina Finder Window
Senseless Chat App
Settings Panel
Simple Media Player
Simple Text Editor
Twitter For OSX
Twitter App Concept
