The underlying secret to beautiful user interface design is realism: making 2D objects on your screen appear to sit in 3D space. Designing beautiful user interfaces has more to do with the why than the how. — This is a wonderful article from Mike Rundle, looking into the thinking behind how realistic user interfaces are crafted. The advice and techniques are invaluable, whether you’re designing software or creating a website. He also provides a downloadable PSD with a few of the examples in action.