CSS3 Rounded Corners using border-radius
Among CSS3's handy new features is the border-radius property, which offers a clean and easy way of adding rounded corners to elements on the page. The rounded corner look can be applied to any or all four corners of an element, and even works with elements with a background image.

Curly Corner Container
There are countless techniques on the web for adding curly/ round corners to DIV containers. The below shows one way to add a curly lower right corner to any DIV on your page. It does so by using relative positioning to slightly offset a DIV to the right and bottom, so its background image, which is a curly image, falls inline with the border of the outer DIV.

Image frames using CSS3 border-image
CSS3 makes it possible to specify an image as an element's border, instead of just a solid color. It takes a single image and then slices and dices it before using the end pieces to make up the border. Very cool!

Image with sliding description panel using CSS3 transitions
This CSS example shows how to add an animated description panel to images that slides open when the mouse rolls over the image using CSS3 transitions.

Pure CSS3 Push Down Panel
This is a CSS3 push down panel that when clicked on reveals some content, pushing the rest of the page's content down in the process. The entire interface is created using CSS only, using a combination of CSS3 shadows, round borders, and CSS2 generated content.