Got a couple of slightly-oldie-but-goodies for you:
A jQuery plugin by Manos Malihutsakis which allows you do to create custom scrollbars for content areas that do some neat things like move their position and size, style them differently, and use easing.
Benjamin De Cock's CSS Playground has a number of stripped down and clever CSS ideas like a slideshow, spinner graphic without images, and some neat navigation ideas.
Caleb Ogden uses some CSS3 to make a submit button look like the browser default in Internet Explorer. Hey, that's one way to get some cross browser consistency.