Recently I've been messing with the cool new features of CSS3 to a client project and I was inspired to see what sort of interface features could be done with it.
The nice things, like drop shadows, gradient background and curved corners, make things look great without having to reach to the image editor, but are hardly revolutionary. Any design that is well planned could already make use of these things and they've been around on the web for ages, though CSS3 certainly makes them far easier to implement.
What really got my attention were transitions.